qwq:32b
Rounds & answers 49
▶ R31 · Bat and ball (the classic reasoning trap) Open round →
Der Ball kostet 0,05 Euro. Der Schläger ist um 1,00 Euro teurer, also 1,05 Euro. Zusammen betragen 0,05 + 1,05 = 1,10 Euro, was den Bedingungen entspricht.
▶ R32 · Four houses, four clues (constraint puzzle) Open round →
Die Farben der Häuser in den Positionen 1 bis 4 sind wie folgt:
1. **Grün** (gemäß Fakt 2).
2. **Rot**
3. **Blau**
4. **Gelb**
### Begründung:
- **Fakt 2** legt direkt fest, dass das grüne Haus an Position 1 steht.
- **Fakt 1** ("Rot liegt direkt links von Blau") und **Fakt 3** ("Gelb liegt direkt rechts von Blau") erfordern, dass die Reihenfolge **Rot-Blau-Gelb** unmittelbar hintereinander folgt.
- Da nur drei Positionen (2, 3 und 4) für diese drei Farben übrig bleiben, muss diese Reihenfolge dort platziert werden:
- Position 2: Rot
- Position 3: Blau
- Position 4: Gelb
Dies erfüllt alle Bedingungen:
- Rot (2) liegt direkt links von Blau (3).
- Gelb (4) liegt direkt rechts von Blau (3).
- Grün ist an Position 1.
Keine anderen Anordnungen sind möglich, da Blau nicht in Position 1 oder 4 stehen kann (wegen der Position des Gelben und Roten).▶ R33 · Idioms that break literal translation (EN→DE) Open round →
1) 'to bite the bullet' → **"die Zähne zusammenbeißen"** 2) 'the ball is in your court' → **"Die Kugel liegt in deinem Gewehrlauf"** 3) 'it's raining cats and dogs' → **"es gießt wie aus Eimern"**
▶ R34 · Constrained taglines (word ban + length cap) Open round →
<think> Okay, der Benutzer will drei Werbe-Claims für eine Bambus-Zahnbürste. Die Regeln sind strikt: maximal sechs Wörter pro Claim, und die Wörter 'nachhaltig' und 'Natur' dürfen nicht vorkommen. Zudem sollen die Claims nummeriert sein und nur die drei Claims ausgeben. Zuerst denke ich mir, dass die Ziele der Bambus-Zahnbürste wahrscheinlich um Umweltfreundlichkeit, Zahnhygiene und praktische Eigenschaften wie Bequemlichkeit oder Effektivität gehen. Da 'nachhaltig' und 'Natur' nicht erlaubt sind, muss ich Synonyme oder indirekte Ausdrücke finden. Vielleicht Begriffe wie 'umweltfreundlich' verwenden, aber das ist nah an 'nachhaltig', daher evtl. 'biodegradable'? Oder 'zerfällt' als替代. Der erste Claim könnte die Biodegradierbarkeit hervorheben. Z.B. "Zerfällt in Wochen, reinigt effektiv." Das sind sechs Wörter, passt. Zweiter Claim könnte auf die Beschaffenheit der Borsten abzielen, w …
Excerpt — the full answer is on the round page.
▶ R35 · Minutes in a (non-leap) year — show the math Open round →
Ein normales Jahr mit 365 Tagen besteht aus:
1. **Berechnung der Stunden pro Jahr**
\( 365 \, \text{Tage} \times 24 \, \text{Stunden/Tage} = 8760 \, \text{Stunden} \).
2. **Umwandlung der Stunden in Minuten**
\( 8760 \, \text{Stunden} \times 60 \, \text{Minuten/Stunde} = 525,\!600 \, \text{Minuten} \).
**Endergebnis:**
\boxed{525600}▶ R36 · Continue the sequence (doubling gaps) Open round →
<think> Okay, let me see. The sequence is 2, 3, 5, 9, 17, and I need to find the next number. Hmm, so first I should look at the differences between the numbers. Let me subtract each number from the one that follows it. Starting with 3 - 2 = 1. Then 5 - 3 = 2. Next, 9 - 5 = 4. After that, 17 - 9 = 8. Wait a second, those differences are 1, 2, 4, 8. That looks like they're doubling each time. So 1 times 2 is 2, then 2 times 2 is 4, 4 times 2 is 8. So if that pattern continues, the next difference should be 16, right? Because 8 times 2 is 16. So adding that to the last number in the sequence, which is 17, plus 16 would give 33. Let me check that again. Let's list the differences again to be sure: between 2 and 3 is +1, 3 to 5 is +2, 5 to 9 is +4, 9 to 17 is +8. Yep, each time the difference doubles. So the next difference is indeed 16, leading to 17 + 16 = 33. Wait, but just to make s …
Excerpt — the full answer is on the round page.
▶ R37 · False friend: 'control' EN→DE Open round →
Bevor wir liefern, muss ich die Testergebnisse überprüfen und gegebenenfalls zwei Bugs beheben.
▶ R38 · Register shift: formal → casual (DE) Open round →
Hey Laura, die Besprechung fällt leider auf morgen 10 Uhr um. Bis dann!
▶ R39 · 40-word product blurb with 3 required words Open round →
Robuster Edelstahl mit modernem Design. Auslaufsicherer Verschluss hält Getränke stundenlang kalt oder warm. Spülmaschinenfestes Material für einfache Reinigung. Praktischer Tragegriff für mobile Nutzung. Perfekt für Fitness, Arbeit oder Reisen.
▶ R40 · isPalindrome (ignore case & non-alphanumerics) Open round →
function isPalindrome(s) {
const processed = s.replace(/[^a-zA-Z0-9]/g, '').toLowerCase();
return processed === processed.split('').reverse().join('');
}▶ R41 · Prose → valid JSON Open round →
{
"name": "Anna Schmidt",
"age": 30,
"city": "Freiburg",
"hobbies": ["Lesen", "Radfahren"],
"newsletterSubscribed": "ja"
}▶ R42 · All but nine (word-problem trap) Open round →
9. Es sind noch 9 Schafe am Leben.
▶ R43 · Five machines (rate-reasoning trap) Open round →
Die Antwort ist 5 Minuten. 5 Maschinen brauchen 5 Minuten für 5 Teile, da jede Maschine 1 Teil in 5 Minuten herstellt. Bei 100 Maschinen arbeitet jede unabhängig und produziert同样 in 5 Minuten je ein Teil. Daraufhin sind nach 5 Minuten genau 100 Teile fertig. Die Zeit hängt nicht von der Anzahl der Maschinen ab, solange Maschinen und Teile proportional skaliert werden.
▶ R44 · Appointment extraction to strict JSON Open round →
[
{
"datum": "2026-08-12",
"uhrzeit": "14:30",
"titel": "Budgetplanung"
},
{
"datum": "2026-09-03",
"uhrzeit": "09:00",
"titel": "Zahnarzttermin"
},
{
"datum": "2026-12-31",
"uhrzeit": "20:30",
"titel": "Silvesterparty"
}
]▶ R45 · Idiom-dense German to natural English Open round →
This isn't ideal, but we shouldn't rock the boat—bottom line, we can live with it.
▶ R46 · Energy conservation on a frictionless incline Open round →
<think> Okay, so I need to solve this physics problem about a block sliding down a frictionless incline. Let me start by understanding what's given and what's being asked. The problem says a 2 kg block starts from rest at the top of a frictionless incline and slides down, dropping a height of 5 meters. We have to use energy conservation and g = 9.8 m/s² to find two things: (a) the block's speed at the bottom, and (b) its kinetic energy at the bottom. Hmm, energy conservation. That usually means that the potential energy at the top will convert into kinetic energy at the bottom, right? Since there's no friction, all the gravitational potential energy should turn into kinetic energy. Let me recall the formulas. Gravitational potential energy (PE) is mass times gravity times height, so PE = mgh. Kinetic energy (KE) is (1/2)mv². Since energy is conserved, the potential energy at the top …
Excerpt — the full answer is on the round page.
▶ R47 · Unit conversion: km/h to m/s and mph Open round →
<think> Okay, so I need to convert the car's speed from kilometers per hour to meters per second and also to miles per hour. Let's see... The car is going 108 km/h. Starting with part (a): converting to meters per second. Hmm, right, because kilometers to meters and hours to seconds. I remember that 1 kilometer is 1000 meters, so maybe I can multiply by that to get meters. And then hours to seconds... there are 60 minutes in an hour and 60 seconds in a minute, so 60 times 60 is 3600 seconds in an hour. So maybe I can divide by 3600 to get seconds? Let me write that out step by step. First, 108 km/h. To convert km to m, multiply by 1000, because 1 km = 1000 m. So 108 km/h * 1000 m/km. That gives me meters per hour. Then to convert hours to seconds, I need to divide by the number of seconds in an hour, which is 3600. So, 108 * 1000 divided by 3600. Let me compute that. Calculating nume …
Excerpt — the full answer is on the round page.
▶ R48 · Low-orbit satellite: speed and period (orbital/Kepler estimate) Open round →
<think> Okay, so I need to figure out the orbital speed and the orbital period of a satellite that's orbiting Earth at an altitude of 400 km. Let me start by recalling what the problem said. They gave Earth's radius as approximately 6371 km and the gravitational parameter μ as 398600 km³/s². The formulas provided are for velocity, v = sqrt(μ/r), and for the period, T = 2πr/v. Alright, let me break this down step by step. First, I need to find the orbital speed. The formula requires the distance from the center of the Earth, which is the Earth's radius plus the altitude of the satellite. The satellite is at 400 km above the Earth's surface, so the total distance r would be Earth's radius (6371 km) plus 400 km. Let me calculate that: r = 6371 km + 400 km = 6771 km. Hmm, okay. So that's the value of r. Now, plugging this into the velocity formula: v = sqrt(μ / r) So substituting the gi …
Excerpt — the full answer is on the round page.
▶ R49 · Ohm's law: resistance and power dissipation Open round →
(a) Using Ohm's Law \( V = IR \), we solve for resistance \( R \):
\[
R = \frac{V}{I} = \frac{12\ \text{V}}{0.5\ \text{A}} = 24\ \Omega
\]
**Answer:** The resistance of the resistor is \(\boxed{24\ \Omega}\).
(b) To find the electrical power dissipated, we use \( P = VI \):
\[
P = V \times I = 12\ \text{V} \times 0.5\ \text{A} = 6\ \text{W}
\]
**Answer:** The electrical power dissipated is \(\boxed{6\ \text{W}}\).▶ R50 · Thin lens equation: image distance and magnification Open round →
<think> Okay, so I need to solve this problem about a converging lens. Let me start by recalling what I know. The question is about a convex lens with a focal length of 10 cm. The object is placed 15 cm in front of the lens, and they want me to find the image distance and the magnification. Also, determine if the image is real or virtual and upright or inverted. Alright, let's start with the thin lens equation. The thin lens equation is 1/f = 1/d_o + 1/d_i. Here, f is the focal length, d_o is the object distance, and d_i is the image distance. The magnification is given by m = -d_i/d_o. So, given values are f = 10 cm and d_o = 15 cm. Let me write that down: f = 10 cm d_o = 15 cm First, part (a) asks for the image distance d_i. I need to rearrange the thin lens equation to solve for d_i. The equation is: 1/f = 1/d_o + 1/d_i So, rearranging to solve for 1/d_i gives: 1/d_i = 1/f - …
Excerpt — the full answer is on the round page.
▶ R51 · Heat required to warm water (specific heat capacity) Open round →
<think> Okay, so I need to figure out how much heat energy is required to raise the temperature of 2 kg of water from 20°C to 80°C. The problem gives me the specific heat capacity of water, which is 4186 J/(kg·K), and the formula Q = m*c*ΔT. Alright, let me start by recalling what each of these variables stands for. First, m is the mass of the substance, which in this case is water. The mass given here is 2 kg. Then c is the specific heat capacity, which tells us how much energy is needed to raise the temperature of 1 kg of the substance by 1 degree Kelvin. Since the temperature is given in Celsius, I remember that the change in temperature (ΔT) in Celsius is the same as in Kelvin, so that's straightforward. The ΔT here would be the final temperature minus the initial temperature. Let me write down the values first: - Mass (m) = 2 kg - Specific heat capacity (c) = 4186 J/(kg·K) - In …
Excerpt — the full answer is on the round page.
▶ R52 · Fermi estimate: how many piano tuners in a 10-million-person city? Open round →
<think> Okay, so I need to estimate the number of professional piano tuners in a city with 10 million people using Fermi estimation. Let me start by breaking this down step by step. First, I need to figure out how many pianos there are in the city. To do that, I should probably start by estimating how many households there are. Since the population is 10 million, I can assume that each household has about 2.5 people on average. That’s a common estimate I’ve heard before. So dividing 10 million by 2.5 gives me the number of households. Let me check that math: 10,000,000 divided by 2.5 is 4,000,000 households. Hmm, maybe a bit high? But okay, let's go with that for now. Next, what percentage of these households actually have a piano? I know that not everyone has a piano, so I need a reasonable fraction. Maybe 1% of households own a piano? That seems plausible. So 1% of 4 million househ …
Excerpt — the full answer is on the round page.
▶ R53 · Why is the sky blue? (conceptual) Open round →
The sky appears blue during the day because of a physical phenomenon called **Rayleigh scattering**. Here's the simple explanation: Sunlight looks white to our eyes, but it’s made up of all the colors of the rainbow. When sunlight enters Earth’s atmosphere, it collides with tiny molecules and particles in the air. These collisions cause the light to scatter in different directions. Blue light has a shorter wavelength and scatters much more easily than other colors like red or yellow. This scattering sends blue light bouncing all over the place in the atmosphere. Since our eyes are seeing this scattered blue light coming from all directions, the sky looks blue to us. Meanwhile, colors with longer wavelengths, like red or orange, aren’t scattered as much. They pass through the atmosphere more directly, which is why sunsets often turn red—the sunlight has to travel through more atmosph …
Excerpt — the full answer is on the round page.
▶ R54 · Time dilation: why do moving clocks run slow? (conceptual, special relativity) Open round →
In special relativity, time dilation occurs because the speed of light is constant for all observers, no matter their motion. Imagine a clock that works by bouncing light between two mirrors. If this clock is moving relative to an observer, the light's path appears longer to the observer—like a diagonal path instead of a straight one. Since the light must travel this extra distance at the same constant speed, the observer concludes that the moving clock is ticking slower. This is why a moving clock is measured to run slow. The symmetry arises because each observer is in their own valid inertial frame of reference. Suppose Alice is stationary and sees Bob’s moving clock as slow. Bob, however, sees Alice as moving and her clock as slow. Neither is "wrong" because both perspectives are equally valid. Special relativity doesn’t privilege one frame over another—every inertial observer’s meas …
Excerpt — the full answer is on the round page.
▶ R101 · Langton's ant building a highway Open round →
<think> Okay, the user wants me to create a self-contained HTML file that simulates Langton's Ant using a canvas. Let me start by recalling the rules of Langton's Ant. The ant is on a grid, starts on a white cell. When on white, it turns right, flips the cell to black, moves forward. On black, turns left, flips to white, moves forward. The goal is to display this on a canvas, with smooth animation, showing step count, and restarting after some time. First, I need the HTML structure. The canvas element is essential. I'll set up a canvas with some size. Maybe 500x500 pixels? That should be visible enough. The user mentioned a strict character limit, so I should keep the code concise. Next, the JavaScript part. I'll need variables for the grid, ant's position and direction. The grid can be an array of arrays. Since the ant moves around, the grid needs to be big enough to handle the movem …
Excerpt — the full answer is on the round page.
▶ R102 · Rule 110 growing line by line Open round →
<think> Okay, the user wants me to create a self-contained HTML file that draws the Rule 110 cellular automaton on a canvas. Let me start by recalling what Rule 110 entails. The rule defines the next state of a cell based on its current state and the two adjacent cells. The rule number 110 in binary is 0b1101110, which corresponds to the decimal 110. The lookup table for Rule 110 is: The binary 110 is 0b01101110, so the rules are as follows: For each triplet of three cells (left, current, right), the next state is determined by: 111 -> 0 110 -> 1 101 -> 1 100 -> 0 011 -> 1 010 -> 1 001 -> 1 000 -> 0 Wait, let me double-check that. The decimal 110 in binary with 8 bits is 01101110. The bits are read from left to right as the possible combinations. The order of the combinations is from 111 to 000. So the mapping is: 111 → 0 (0) 110 → 1 (1) 101 → 1 (1) 100 → 0 (2) 011 → 1 (3) 010 → 1 …
Excerpt — the full answer is on the round page.
▶ R103 · Wireworld with a clock and a diode Open round →
<think> Okay, I need to create a self-contained HTML file that simulates a Wireworld circuit using a canvas. Let me start by recalling the Wireworld rules. Each cell can be in four states: empty (0), conductor (1), electron head (2), or electron tail (3). The rules are: 1. Head becomes a tail. 2. Tail becomes conductor. 3. Conductor becomes a head if exactly one or two of its eight neighbors are heads; else stays conductor. 4. Empty stays empty. The task is to create a circuit with a closed loop acting as a clock and a diode that allows pulses in one direction. The simulation should start automatically with a single electron, display step count and electron count, use smooth animation via requestAnimationFrame, and restart with a new random instance after finishing. First, the HTML structure. I'll need a canvas element and some divs for displaying step and electron count. The script …
Excerpt — the full answer is on the round page.
▶ R104 · Abelian sandpile toppling Open round →
<think> Okay, I need to create a self-contained HTML file that simulates an abelian sandpile on a canvas. The user specified some key requirements: the sandpile should start at the center cell, topple when a cell has 4 or more grains, distribute grains to neighbors, color cells based on their grain count, track the number of grains dropped and topplings, use requestAnimationFrame for smooth animation, and restart with a new random instance when finished. Also, no external libraries and keep it under 7000 characters. First, I'll structure the HTML with a canvas element. The main part will be the JavaScript code. Let me outline the steps: 1. **Initialize the grid**: The grid should be a 2D array. Since the simulation starts at the center, the grid's size needs to be odd so there's a clear center. Let's pick a size like 201x201 (so the center is at [100][100]). But this might be too big. …
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▶ R105 · Brian's Brain Open round →
<think> Okay, let's tackle this problem. The user wants a self-contained HTML file that implements Brian's Brain cellular automaton on a canvas. The requirements are pretty specific, so I need to break them down step by step. First, the grid needs to be at least 120x120. That's manageable. The cellular automaton has three states: on, dying, and off. Each state transitions based on the rules given. The key here is to handle the state transitions correctly without overwriting the data prematurely. The user mentioned using a second buffer, so I'll need two grids: one for the current state and another to compute the next step. That way, we don't read from the current buffer as we write to the next. The canvas needs to draw these three states with distinct colors. Let me think about color choices. Maybe red for on, yellow for dying, and white for off? The user didn't specify colors, but th …
Excerpt — the full answer is on the round page.
▶ R106 · Truchet tiles rearranging Open round →
<think> Okay, I need to create a self-contained HTML file that uses a canvas to display Truchet tiles. The tiles should form a grid where each cell has two quarter-circle arcs in one of two orientations. The animation should randomly re-roll a few tiles each frame with a cross-fade effect, making the curves reorganize smoothly. Also, it should show the grid size and the number of flipped tiles, use requestAnimationFrame for smooth animation, start immediately, and restart once finished. No external libraries, and the entire HTML must be under 7000 characters. First, the basic structure. The HTML needs a canvas element and some divs to display grid size and flipped count. The script will handle the animation. Truchet tiles: each tile can be in two states. The two orientations can be represented by a binary value, like 0 and 1. The quarter-circles would be drawn based on this value. For …
Excerpt — the full answer is on the round page.
▶ R107 · Hilbert curve drawing itselfDNF Open round →
▶ R108 · Interlocking star pattern on a grid Open round →
<think> Okay, let's tackle this problem. The user wants an HTML file that creates an Islamic-style star pattern on a canvas. The key points are: using regular polygons on a grid, extending edges to form interlaced stars and rosettes, rotating slowly, showing grid size and stroke count, using requestAnimationFrame for smooth animation, no user input, restarting when finished, no external libraries. And it has to be self-contained. First, I need to figure out how to create the grid. Islamic patterns often use grids of polygons like octagons or dodecagons. Maybe a grid of squares with octagons in the corners? Or perhaps hexagons? Wait, the user mentioned regular polygons. Maybe a square grid where each cell has a central polygon with edges extending? Hmm, the edges need to be extended until they meet neighbors' edges. So when you draw the edges of a polygon and extend them, they should f …
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▶ R109 · Moire from two rotating rasters Open round →
<think> Okay, the user wants me to create an HTML file that displays a moiré effect using a canvas. The main goal is to have two concentric rings that are identical, one on top of the other. The challenge is to rotate and shift one of them so that the interference bands move across the image. Also, the rings should be fine enough so that the interference is visible but the individual rings don't blur into each other. First, I need to set up the canvas element in the HTML. Since it's self-contained, I have to include all the JavaScript inside the script tags. The moiré effect is created by the interference between two patterns. In this case, concentric circles. So, the approach will be to draw two sets of rings, one rotated and shifted relative to the other. I'll start by initializing the canvas and getting the 2D context. The canvas size should be reasonable, maybe 400x400 pixels. The …
Excerpt — the full answer is on the round page.
▶ R110 · Penrose-style aperiodic tiling growingDNF Open round →
▶ R111 · Ant colony laying pheromone trails Open round →
<think> Alright, I need to create an HTML file that simulates an ant colony using a canvas. The user wants it self-contained, so all the code has to be in one file. Let me break down the requirements step by step. First, the basic structure: I'll start with the HTML5 doctype, then a canvas element. The JavaScript will handle everything else. The key components are the ants, the pheromone trails, the nest, and the food source. The ants should start at the nest, wander around, and follow pheromones. When an ant finds food, it should return to the nest, leaving a trail. The pheromones need to evaporate over time, so that old paths fade away. The user also wants the count of ants and food carried home to be displayed. I'll need to use requestAnimationFrame for smooth animation. The simulation should start immediately and can be restarted by reloading the page. No external libraries, so …
Excerpt — the full answer is on the round page.
▶ R112 · Physarum slime-mould network Open round →
<think> Okay, I need to create a self-contained HTML file that simulates a Physarum-style agent. The user wants thousands of particles moving on a canvas, sensing the trail map ahead, turning towards the strongest signal, moving forward, and depositing to the trail. The trail should be blurred and faded each step. The result should show branching vein networks. Also, need to display agent count and step number, use requestAnimationFrame for smooth animation, and restart automatically. No comments or external libraries. First, I'll start with the HTML structure. The canvas element is straightforward. Then, the script section will handle all the logic. The Physarum simulation typically uses particles that follow a trail they lay down. Each particle has a direction and position. The trail is represented as a grid that gets updated and blurred. Variables needed: canvas context, trail arr …
Excerpt — the full answer is on the round page.
▶ R113 · Predator and prey on a shared field Open round →
<think> Okay, I need to create a self-contained HTML file that simulates predators and prey on a canvas. Let me start by understanding the requirements. The user wants prey to graze on regrowing food, multiply where food is plentiful, predators to chase nearby prey, eat them, lose energy over time, and multiply when well-fed. The populations should oscillate, and I have to show both counts. The animation should use requestAnimationFrame, no user input, starts immediately, and restarts when finished. No external libraries, and the code must be under 7000 characters. First, I'll set up the basic HTML structure with a canvas element. I'll need a head section with a title and a body with the canvas. The canvas will be the main area for the simulation. Next, the JavaScript part. I'll start by getting the canvas context and setting up some constants. The canvas size can be set to 800x600 fo …
Excerpt — the full answer is on the round page.
▶ R114 · Traffic jam from nothing Open round →
<think> Okay, I need to create a self-contained HTML file that simulates traffic on a ring road using the Nagel-Schreckenberg model. Let me recall the rules. The model has cars moving on a single lane, and each step involves acceleration, deceleration to avoid collisions, random slowing, and then moving. The cars should be evenly spaced initially to form a phantom jam. The visualization should show the ring road and color cars based on their speed. First, I'll structure the HTML. The canvas element must be included. I'll set the width and height attributes, maybe 800x400px. Then, the JavaScript part will handle the simulation and animation. I need to initialize the canvas context. Let's use a 2D context. The main loop will use requestAnimationFrame for smooth animation. For the traffic model, the road is a ring, so the positions wrap around. I need an array of cars. Each car has a po …
Excerpt — the full answer is on the round page.
▶ R115 · Crowd leaving through a bottleneck Open round →
<think> Okay, I need to create an HTML file that simulates a crowd moving towards a narrow exit with forces acting on them. Let me think through the steps. First, the HTML structure. I'll have a canvas element and a few divs to display the count and flow rate. The canvas will handle the animation. Since the user wants it self-contained, all code has to be inline. Next, the JavaScript part. I need to model each person as an object with position, velocity, and maybe acceleration. Each person should have a force towards the door and repulsion from others and walls. The door is a single narrow exit, so maybe the bottom edge of the canvas? Let me define the door position. The people should be attracted to the door's center, perhaps with a gravitational force. The repulsion from others can be calculated using distance between each pair of people. Also, walls are the edges of the canvas, so …
Excerpt — the full answer is on the round page.
▶ R116 · Bresenham circles and lines, pixel by pixel Open round →
<think> Okay, I need to create a self-contained HTML file that uses Bresenham's midpoint line and circle algorithms with integer arithmetic. The animation should draw a rotating spoke pattern of lines and concentric circles, showing each pixel step. The user wants the pixel count displayed, smooth animation with requestAnimationFrame, and it should restart automatically when done. No external libraries or comments. Let me think through the steps. First, the HTML structure. I'll need a canvas element with some styling to make it visible. The JavaScript will handle the drawing. Since we have to use ImageData and set individual pixels, I'll need to get the canvas context, create an ImageData object, and update it every frame. For Bresenham's line algorithm: the midpoint line routine uses integer calculations. The standard algorithm uses decision variables to determine the next pixel. I'll …
Excerpt — the full answer is on the round page.
▶ R117 · De Casteljau construction of a Bezier curve Open round →
<think> Okay, I need to create a self-contained HTML file that animates the De Casteljau construction for a cubic Bezier curve using a canvas. Let me start by recalling how De Casteljau's algorithm works. For a cubic Bezier with four control points, at each parameter t, we compute intermediate points by linear interpolation between the control points step by step until we get the final point on the curve. The user wants the control points to drift slowly. So I need to define four control points that change over time. Maybe I can make them move in random directions or follow some path, but keep it simple. Maybe each point has a velocity vector that's updated periodically. But since the animation uses requestAnimationFrame, I can adjust their positions each frame slightly. Let's think of each point having a small random movement each frame. The animation should start immediately and loo …
Excerpt — the full answer is on the round page.
▶ R118 · Sutherland-Hodgman polygon clippingDNF Open round →
▶ R119 · Floyd-Steinberg dithering a gradient Open round →
Here's a JavaScript implementation of Floyd-Steinberg dithering applied to an image generated with a sinusoidal pattern. The code creates a canvas and displays the dithered image.
```javascript
function ditherImage(width, height, frame) {
const step = 16;
const pixelCount = width * height;
const floatData = new Float64Array(4 * pixelCount);
const data = new Uint8ClampedArray(4 * pixelCount);
// Initialize with a sinusoidal function
for (let y = 0; y < height; y++) {
for (let x = 0; x < width; x++) {
const index = (y * width + x) * 4;
const val = Math.sin(x * 0.1 + y * 0.1 + frame * 0.5) * 127 + 128;
floatData[index] = val; // Red
floatData[index + 1] = val; // Green
floatData[index + 2] = val; // Blue
floatData[index + 3] = 255; // Alpha
}
}
// Apply Floyd-Steinberg …Excerpt — the full answer is on the round page.
▶ R120 · Scanline fill of a self-intersecting polygon Open round →
<think> Okay, I need to create an HTML file that draws a rotating and deforming polygon using a scanline algorithm. The key points are: the polygon is self-intersecting, the fill uses even-odd rule via scanlines, show scanline count and spans filled per frame, and it should animate smoothly with requestAnimationFrame. Also, it must be self-contained, under 7000 characters, no external libraries, and restart on finish. First, I need the HTML5 canvas setup. The canvas element is straightforward. Then, the JavaScript part. Let me think about the steps. 1. **Setup Canvas**: Get the canvas and context, set size to something like 500x500. Maybe scale the context to make it easier. 2. **Polygon Definition**: The polygon needs to rotate and deform. Maybe use a regular polygon but rotate its vertices. To deform, perhaps add some random offsets or use a sine wave for the vertices' positions. T …
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▶ R121 · A* pathfinding search across an obstacle grid Open round →
<think> Okay, so I need to create an HTML file that animates the A* search algorithm on a canvas. The user specified it should be self-contained, strict limit of 7000 characters, no external libraries, and no comments. Let me start by breaking down the requirements. First, the HTML structure. It should have a canvas element, and some text elements to display the nodes expanded and path length. Maybe use divs for the text. The canvas needs some styling to be centered and visible. Then, the JavaScript part. I need to set up the grid, with obstacles, start and goal points. The grid should be randomly generated each time. The A* algorithm needs to be implemented with pathfinding. The animation should use requestAnimationFrame for smoothness. Also, when the path is found or it's impossible, it should restart with a new grid. Let me think about the grid structure. Each cell can be an objec …
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▶ R122 · Randomized maze generation via recursive backtracking Open round →
<think> Okay, I need to create a self-contained HTML file that animates a recursive backtracking maze generation on a canvas. Let me start by recalling how recursive backtracking works for maze generation. The algorithm starts at a cell, randomly selects an unvisited neighbor, carves a passage to it, pushes the current cell to the stack, and moves to the new cell. When there are no more unvisited neighbors, it backtracks using the stack until it finds a cell with unvisited neighbors again. The process continues until all cells are visited. First, I'll structure the HTML with a canvas element. Since no external libraries are allowed, I'll use the canvas API directly. The animation should use requestAnimationFrame for smoothness. I need to handle the canvas setup, the maze grid, and the backtracking stack. I'll start by defining variables: the canvas context, cell size, grid dimensions. …
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▶ R123 · Breadth-first flood fill spreading through a region Open round →
<think> Okay, let's tackle this problem. The user wants a self-contained HTML file that animates a breadth-first flood fill on a canvas. The animation should show the wave spreading outward from a starting cell, coloring each cell based on its distance from the seed. It needs to restart with a new grid once it's done, and use requestAnimationFrame for smooth animation without any user input. Also, no external libraries and the total character count must be under 7000. First, I need to structure the HTML file with a canvas element. The main script will handle the animation loop. Let me start by setting up the basic HTML structure. The canvas needs to be sized appropriately, maybe 400x400 pixels to keep things manageable. Next, the JavaScript part. I need to generate a grid of cells, some blocked and some open. To make it irregular, maybe use a 2D array where each cell has a 'blocked' pr …
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▶ R124 · Dijkstra's shortest path over weighted terrain Open round →
<think> Okay, let's tackle this problem. The user wants an HTML file that animates Dijkstra's algorithm on a canvas. Hmm, I need to create a self-contained HTML file with all the code inside. Let me break down the requirements step by step. First, the canvas needs a grid with random movement costs. Each cell's color should be lighter for cheaper costs and darker for expensive ones. So, generating a 2D array for the grid with random numbers between 1 and maybe 10? I'll have to think about the range. The user said movement cost, so probably higher numbers mean it's more expensive. So lighter cells (like white) for lower costs and darker for higher. Maybe a grayscale color based on the cost normalized. Next, Dijkstra's algorithm steps: starting from a source, expanding to the cheapest unsettled cell each time. The settled cells need to be colored by their accumulated distance. The target …
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▶ R125 · Voronoi diagram growing by multi-source flood fill Open round →
<think> Okay, I need to create an HTML file that animates a Voronoi diagram using a multi-source BFS flood fill. Let me think through the steps. First, the Voronoi diagram is made by having seed points that expand outward, and each cell is assigned to the nearest seed. To animate this, I can use a grid where each cell is filled by the first seed that reaches it. The animation should use requestAnimationFrame for smoothness. The user wants the animation to start immediately, loop continuously, and restart when done. The seed points should be scattered randomly each time. Also, I have to display the number of cells claimed, which I guess means the number of seeds, but maybe it's the total cells? Wait, the user says "show the number of cells claimed"—maybe each seed's area is a cell, so the number of seeds would be the count. Hmm, but maybe it counts all cells? Probably the seeds count a …
Excerpt — the full answer is on the round page.