GraphSimulation/mini.html at master · harshpalas/GraphSimulation · GitHub

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<!DOCTYPE html>
<html lang="en" >
<head>
  <meta charset="UTF-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
  <title>MST Visualizer (Prim & Kruskal) - Pause & Slow Explanation</title>
  <script src="https://cdn.tailwindcss.com"></script>
  <style>
    svg {
      background-color: #374151;
      border-radius: 12px;
      box-shadow: 0 4px 8px rgb(0 0 0 / 0.5);
    }
    #info {
  background-color: #1e293b;
  border-radius: 8px;
  padding: 12px;
  max-height: 60vh;
  overflow-y: auto;
  white-space: pre-wrap;
  font-family: monospace;
  font-size: 14px;
  line-height: 1.4;
  box-shadow: inset 0 0 5px #0f172a;
  user-select: text;
  margin-top: 1rem;
  transition: max-height 0.3s ease;
}

    button:disabled {
      opacity: 0.5;
      cursor: not-allowed;
    }
  </style>
</head>
<body class="bg-gray-900 text-white min-h-screen flex items-center justify-center p-6">
  <div class="w-[1400px] bg-gray-800 p-6 rounded-xl shadow-xl flex gap-6">
    <!-- Sidebar -->
    <div class="w-64 flex flex-col gap-4 max-h-[90vh] overflow-y-auto">
      <h1 class="text-3xl font-bold mb-4">MST Visualizer</h1>
      <button id="runPrim" class="bg-green-600 hover:bg-green-700 rounded py-3 px-4 font-semibold">Run Prim's MST</button>
      <button id="runKruskal" class="bg-green-600 hover:bg-green-700 rounded py-3 px-4 font-semibold">Run Kruskal's MST</button>
      <button id="pausePlay" class="bg-yellow-600 hover:bg-yellow-700 rounded py-3 px-4 font-semibold mt-4">Pause</button>
      <button id="reset" class="bg-gray-400 hover:bg-gray-500 rounded py-3 px-4 font-semibold mt-6">Reset</button>
      <div id="info"></div>
    </div>

    <!-- Graph Area -->
    <div class="flex-1">
      <svg id="graph" width="1000" height="700"></svg>
    </div>
  </div>

<script>
  // === Setup and data ===
  const svg = document.getElementById("graph");
  const info = document.getElementById("info");

  const positions = [
    {x: 150, y: 100}, {x: 300, y: 150}, {x: 450, y: 100}, {x: 600, y: 150}, {x: 750, y: 100},
    {x: 150, y: 400}, {x: 300, y: 350}, {x: 450, y: 400}, {x: 600, y: 350}, {x: 750, y: 400}
  ];

  const edges = [
    [0,1, 4], [0,5, 2], [1,2, 6], [1,6, 3],
    [2,3, 5], [2,7, 4], [3,4, 2], [3,8, 6],
    [4,9, 3], [5,6, 7], [6,7, 4], [7,8, 5],
    [8,9, 2], [5,7, 8], [1,5, 1], [6,8, 3], [0,2, 9]
  ];

  const n = positions.length;
  const adj = Array.from({length: n}, () => []);
  for(const [u,v,w] of edges){
    adj[u].push({to:v, w});
    adj[v].push({to:u, w});
  }

  // === Draw graph function ===
  function drawGraph(mstEdges = [], highlightNode = -1, highlightEdge = null){
    svg.innerHTML = "";
    for(const [u,v,w] of edges){
      const p1 = positions[u];
      const p2 = positions[v];
      const isMST = mstEdges.some(e => (e[0] === u && e[1] === v) || (e[0] === v && e[1] === u));
      const isHighlightEdge = highlightEdge && ((highlightEdge[0] === u && highlightEdge[1] === v) || (highlightEdge[0] === v && highlightEdge[1] === u));
      const line = document.createElementNS("http://www.w3.org/2000/svg", "line");
      line.setAttribute("x1", p1.x);
      line.setAttribute("y1", p1.y);
      line.setAttribute("x2", p2.x);
      line.setAttribute("y2", p2.y);
      line.setAttribute("stroke", isHighlightEdge ? "#f97316" : (isMST ? "#3b82f6" : "#9ca3af"));
      line.setAttribute("stroke-width", isMST || isHighlightEdge ? 5 : 2);
      svg.appendChild(line);

      // Edge weight label with offset for clarity
      const midX = (p1.x + p2.x) / 2;
      const midY = (p1.y + p2.y) / 2;
      const dx = p2.y - p1.y;
      const dy = p1.x - p2.x;
      const len = Math.sqrt(dx * dx + dy * dy);
      const offset = 12;
      const tx = midX + (dx / len) * offset;
      const ty = midY + (dy / len) * offset;

      const text = document.createElementNS("http://www.w3.org/2000/svg", "text");
      text.setAttribute("x", tx);
      text.setAttribute("y", ty);
      text.setAttribute("fill", isHighlightEdge ? "#f97316" : (isMST ? "#3b82f6" : "#f9fafb"));
      text.setAttribute("font-size", "14");
      text.setAttribute("font-weight", "bold");
      text.setAttribute("text-anchor", "middle");
      text.textContent = w;
      svg.appendChild(text);
    }

    for(let i=0; i<n; i++){
      const p = positions[i];
      const circle = document.createElementNS("http://www.w3.org/2000/svg", "circle");
      circle.setAttribute("cx", p.x);
      circle.setAttribute("cy", p.y);
      circle.setAttribute("r", 22);
      circle.setAttribute("fill", i === highlightNode ? "#3b82f6" : "#e5e7eb");
      circle.setAttribute("stroke", "#1e293b");
      circle.setAttribute("stroke-width", "3");
      svg.appendChild(circle);

      const text = document.createElementNS("http://www.w3.org/2000/svg", "text");
      text.setAttribute("x", p.x);
      text.setAttribute("y", p.y + 7);
      text.setAttribute("text-anchor", "middle");
      text.setAttribute("font-size", "20");
      text.setAttribute("font-weight", "bold");
      text.setAttribute("fill", i === highlightNode ? "#fff" : "#000");
      text.textContent = i;
      svg.appendChild(text);
    }
  }

  // === Pause/play control variables ===
  let isPaused = false;
  const pausePlayBtn = document.getElementById("pausePlay");
  let waitingResolve = null;

  pausePlayBtn.onclick = () => {
    isPaused = !isPaused;
    pausePlayBtn.textContent = isPaused ? "Play" : "Pause";
    if(!isPaused && waitingResolve) {
      waitingResolve();
      waitingResolve = null;
    }
  };

  // Controlled delay respecting pause state
  async function controlledDelay(ms){
    let start = Date.now();
    while(true){
      if(!isPaused && Date.now() - start >= ms) break;
      if(isPaused){
        await new Promise(resolve => {
          waitingResolve = resolve;
        });
        waitingResolve = null;
        start = Date.now();
      }
      await new Promise(r => setTimeout(r, 100));
    }
  }


  async function appendLineWithTypewriter(line, delay=60){
    return new Promise(resolve => {
      let i = 0;
      function type(){
        if(isPaused) {
          waitingResolve = () => {
            waitingResolve = null;
            type();
          };
          return;
        }
        if(i < line.length){
          info.textContent += line.charAt(i);
          i++;
          info.scrollTop = info.scrollHeight;
          setTimeout(type, delay);
        } else {
          info.textContent += "\n";
          info.scrollTop = info.scrollHeight;
          resolve();
        }
      }
      type();
    });
  }

  // Disable/enable buttons
  function disableButtons(disabled){
  ["runPrim", "runKruskal", "reset"].forEach(id => {
    const btn = document.getElementById(id);
    btn.disabled = disabled;
  });

  if (!disabled) {
    isPaused = false;
    pausePlayBtn.textContent = "Pause";
  }
}


  async function runPrimsMST(startNode){
    disableButtons(true);
    info.textContent = "";
    await appendLineWithTypewriter("Welcome to Prim's Minimum Spanning Tree algorithm!\n");
    await appendLineWithTypewriter(`We start from node ${startNode}.\n`);
    await appendLineWithTypewriter("Prim's algorithm builds a MST by growing one connected component.\nIt repeatedly adds the smallest edge that connects a new node to the MST.\n");
    await controlledDelay(1500);

    const selected = Array(n).fill(false);
    const key = Array(n).fill(Infinity);
    const parent = Array(n).fill(-1);
    key[startNode] = 0;
    let mstEdges = [];

    for(let count=0; count < n; count++){
      let u = -1;
      let minKey = Infinity;
      for(let v=0; v<n; v++){
        if(!selected[v] && key[v]<minKey){
          minKey = key[v];
          u = v;
        }
      }
      selected[u] = true;

      if(parent[u] !== -1) {
        mstEdges.push([parent[u], u]);
        await appendLineWithTypewriter(`Added edge (${parent[u]}, ${u}) to MST because it has the smallest weight ${minKey} connecting a new node.`);
      } else {
        await appendLineWithTypewriter(`Starting node ${u} is now included in the MST.`);
      }

      drawGraph(mstEdges, u);
      await controlledDelay(3500);

      await appendLineWithTypewriter(`Checking all edges from node ${u} to see if we can update cheaper edges to other nodes not in MST yet.`);
      for(const {to:v,w} of adj[u]){
        if(!selected[v] && w < key[v]){
          await appendLineWithTypewriter(`Found edge (${u}, ${v}) with weight ${w} cheaper than current key ${key[v]} for node ${v}. Updating key and parent.`);
          key[v] = w;
          parent[v] = u;
        }
      }
      await controlledDelay(3500);
    }
    await appendLineWithTypewriter("\nAll nodes are included. Prim's MST is complete!");
    disableButtons(false);
  }

  // Union-Find structure for Kruskal's algorithm
  class UnionFind {
    constructor(size){
      this.parent = Array(size).fill(0).map((_,i)=>i);
      this.rank = Array(size).fill(0);
    }
    find(x){
      if(this.parent[x] !== x) this.parent[x] = this.find(this.parent[x]);
      return this.parent[x];
    }
    union(x,y){
      const rx = this.find(x);
      const ry = this.find(y);
      if(rx === ry) return false;
      if(this.rank[rx] < this.rank[ry]){
        this.parent[rx] = ry;
      } else if(this.rank[ry] < this.rank[rx]){
        this.parent[ry] = rx;
      } else {
        this.parent[ry] = rx;
        this.rank[rx]++;
      }
      return true;
    }
  }


  async function runKruskalMST(){
    disableButtons(true);
    info.textContent = "";
    await appendLineWithTypewriter("Welcome to Kruskal's Minimum Spanning Tree algorithm!\n");
    await appendLineWithTypewriter("Kruskal's algorithm builds a MST by sorting all edges by weight,\nthen adding edges one by one, skipping those that form a cycle.\n");
    await controlledDelay(1500);

    const sortedEdges = edges.slice().sort((a,b) => a[2] - b[2]);
    const uf = new UnionFind(n);
    let mstEdges = [];

    for(let i=0; i<sortedEdges.length; i++){
      const [u,v,w] = sortedEdges[i];
      drawGraph(mstEdges, -1, [u,v]);
      await appendLineWithTypewriter(`Considering edge (${u}, ${v}) with weight ${w}.`);
      await controlledDelay(3500);

      if(uf.union(u,v)){
        mstEdges.push([u,v]);
        drawGraph(mstEdges, -1, [u,v]);
        await appendLineWithTypewriter(`Edge (${u}, ${v}) added to MST as it does not create a cycle.`);
        await controlledDelay(3500);
        if(mstEdges.length === n-1) break;
      } else {
        await appendLineWithTypewriter(`Edge (${u}, ${v}) skipped because it would create a cycle in the MST.`);
        await controlledDelay(3500);
      }
    }

    await appendLineWithTypewriter("\nAll nodes connected without cycles. Kruskal's MST is complete!");
    drawGraph(mstEdges, -1, null);
    disableButtons(false);
  }

  // === Button handlers ===
  document.getElementById("runPrim").onclick = () => {
    const input = prompt(`Enter starting node (0 to ${n - 1}):`);
    const start = parseInt(input);
    if (isNaN(start) || start < 0 || start >= n) {
      alert("Invalid node. Please enter a number between 0 and " + (n - 1));
      return;
    }
    runPrimsMST(start);
  };

  document.getElementById("runKruskal").onclick = () => {
    runKruskalMST();
  };

  document.getElementById("reset").onclick = () => {
  isPaused = false;
  pausePlayBtn.textContent = "Pause";
  info.textContent = "";
  svg.innerHTML = "";
  drawGraph(); // redraw the initial unhighlighted graph
  disableButtons(false); // enable all buttons again
};


  // Initial draw to show graph
  drawGraph();

</script>

</body>
</html>