leetcode-visual/binary-tree-travel.html at main · houbb/leetcode-visual · GitHub

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<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8" />
<title>二叉树遍历可视化</title>
<style>
  body {
    background-color: #0d1117;
    color: #c9d1d9;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  h1 {
    color: #58a6ff;
    text-shadow: 0 0 10px #58a6ff;
    margin-bottom: 10px;
  }
  .controls {
    margin-bottom: 20px;
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
    justify-content: center;
  }
  input.input-box, select.input-box {
    background-color: #161b22;
    border: 1px solid #30363d;
    border-radius: 6px;
    color: white;
    padding: 8px 12px;
    font-size: 14px;
    min-width: 120px;
  }
  button.button {
    background: linear-gradient(90deg, #58a6ff, #1f6feb);
    border: none;
    padding: 10px 20px;
    border-radius: 6px;
    color: white;
    cursor: pointer;
    font-weight: bold;
    font-size: 16px;
    transition: 0.3s;
  }
  button.button:hover {
    box-shadow: 0 0 12px #58a6ff;
    transform: translateY(-2px);
  }
  .container {
    width: 100%;
    max-width: 1400px;
    display: flex;
    gap: 20px;
  }
  .tree-container, .log-container {
    background-color: #161b22;
    border-radius: 12px;
    box-shadow: 0 0 20px rgba(88, 166, 255, 0.3);
    padding: 20px;
    box-sizing: border-box;
  }
  .tree-container {
    flex: 1;
    position: relative;
    min-height: 520px;
    overflow: auto;
  }
  svg {
    position: absolute;
    top: 0; left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
  }
  .tree {
    position: relative;
    width: 100%;
    height: 500px;
  }
  .node {
    background-color: #21262d;
    color: white;
    border-radius: 50%;
    width: 50px;
    height: 50px;
    line-height: 50px;
    text-align: center;
    font-weight: 600;
    box-shadow: 0 0 15px #58a6ff;
    user-select: none;
    cursor: default;
    transition: all 0.3s ease;
    position: absolute;
    transform: translate(-50%, -50%);
    z-index: 2;
  }
  .node.highlight {
    background-color: #58a6ff;
    box-shadow: 0 0 25px #58a6ff;
    color: #000;
    transform: translate(-50%, -50%) scale(1.1);
  }
  .log-container {
    width: 400px;
    display: flex;
    flex-direction: column;
  }
  .log {
    flex: 1;
    background-color: #0d1117;
    border-radius: 10px;
    padding: 15px;
    font-family: monospace;
    font-size: 14px;
    color: #0f0;
    overflow-y: auto;
    height: 500px;
    white-space: pre-wrap;
  }
  .assist {
    margin-top: 15px;
    background-color: #21262d;
    border-radius: 8px;
    padding: 12px;
    font-family: monospace;
    font-size: 14px;
    color: #58a6ff;
    min-height: 60px;
  }
  a {
    margin-top: 12px;
    color: #58a6ff;
    text-decoration: none;
    font-size: 14px;
    align-self: flex-start;
  }
</style>
</head>
<body>

<h1>二叉树遍历可视化</h1>

<div class="controls">
  <input id="treeInput" class="input-box" placeholder='输入数组，如：[1,2,3,null,5]' value='[1,2,3,4,5,6,7]' />
  <select id="traverseType" class="input-box">
    <option value="preorder">前序遍历</option>
    <option value="inorder">中序遍历</option>
    <option value="postorder">后序遍历</option>
    <option value="levelorder">层级遍历</option>
  </select>
  <select id="mode" class="input-box">
    <option value="recursive">递归</option>
    <option value="iterative" selected>迭代</option>
  </select>
  <input id="interval" class="input-box" type="number" value="1000" min="100" step="100" />
  <button class="button" onclick="start()">开始可视化</button>
</div>

<div class="container">
  <div class="tree-container" id="treeContainer">
    <svg id="linesSvg"></svg>
    <div id="tree" class="tree"></div>
  </div>
  <div class="log-container">
    <div id="log" class="log"></div>
    <div id="assist" class="assist">辅助信息：<br>栈/队列：[]<br>结果：[]</div>
    <a href="index.html">返回首页</a>
  </div>
</div>

<script>
  let treeData = [];
  let nodes = [];
  let nodePositions = [];
  const NODE_SIZE = 50;
  const LEVEL_HEIGHT = 110;

  function getTreeHeight(arr) {
    let n = arr.length;
    let height = 0;
    while ((1 << height) - 1 < n) height++;
    return height;
  }

  function calcNodePositions(arr) {
    let height = getTreeHeight(arr);
    let positions = new Array(arr.length).fill(null);

    function helper(idx, depth, left, right) {
      if (idx >= arr.length || arr[idx] === null) return;
      let x = (left + right) / 2;
      let y = depth * LEVEL_HEIGHT + NODE_SIZE / 2 + 10;
      positions[idx] = { x, y };
      helper(2 * idx + 1, depth + 1, left, x);
      helper(2 * idx + 2, depth + 1, x, right);
    }

    helper(0, 0, 0, 1000);
    return positions;
  }

  function renderTree(arr) {
    const treeEl = document.getElementById('tree');
    const svg = document.getElementById('linesSvg');
    treeEl.innerHTML = '';
    svg.innerHTML = '';
    nodes = [];
    nodePositions = [];

    if (!arr.length) return;

    const container = document.getElementById('treeContainer');
    const containerWidth = container.clientWidth || 1000;
    const containerHeight = getTreeHeight(arr) * LEVEL_HEIGHT + 60;
    treeEl.style.width = containerWidth + 'px';
    treeEl.style.height = containerHeight + 'px';
    svg.style.width = containerWidth + 'px';
    svg.style.height = containerHeight + 'px';

    nodePositions = calcNodePositions(arr);

    for (let i = 0; i < arr.length; i++) {
      if (!nodePositions[i]) continue;
      let pos = nodePositions[i];
      pos.x = (pos.x / 1000) * containerWidth;
      pos.y = pos.y;
    }

    for (let i = 0; i < arr.length; i++) {
      if (arr[i] === null || arr[i] === undefined) continue;
      let nodeEl = document.createElement('div');
      nodeEl.className = 'node';
      nodeEl.textContent = arr[i];
      nodeEl.style.left = nodePositions[i].x + 'px';
      nodeEl.style.top = nodePositions[i].y + 'px';
      treeEl.appendChild(nodeEl);
      nodes[i] = nodeEl;
    }

    for (let i = 0; i < arr.length; i++) {
      if (arr[i] === null || arr[i] === undefined) continue;
      let leftChild = 2 * i + 1;
      let rightChild = 2 * i + 2;
      if (leftChild < arr.length && arr[leftChild] !== null && arr[leftChild] !== undefined) {
        drawLine(svg, nodePositions[i], nodePositions[leftChild]);
      }
      if (rightChild < arr.length && arr[rightChild] !== null && arr[rightChild] !== undefined) {
        drawLine(svg, nodePositions[i], nodePositions[rightChild]);
      }
    }
  }

  function drawLine(svg, start, end) {
    let line = document.createElementNS("http://www.w3.org/2000/svg", "line");
    line.setAttribute('x1', start.x);
    line.setAttribute('y1', start.y);
    line.setAttribute('x2', end.x);
    line.setAttribute('y2', end.y);
    line.setAttribute('stroke', '#58a6ff');
    line.setAttribute('stroke-width', '3');
    line.setAttribute('stroke-linecap', 'round');
    line.style.filter = 'drop-shadow(0 0 5px #58a6ff)';
    svg.appendChild(line);
  }

  function log(msg) {
    const logEl = document.getElementById('log');
    logEl.innerHTML += msg + '\n';
    logEl.scrollTop = logEl.scrollHeight;
  }

  function updateAssist(stack, result) {
    const assistEl = document.getElementById('assist');
    assistEl.innerHTML = `辅助信息：<br>栈/队列：[${stack.join(', ')}]<br>结果：[${result.join(', ')}]`;
  }

  function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
  }

  async function highlightNode(idx, duration) {
    if (!nodes[idx]) return;
    nodes[idx].classList.add('highlight');
    await sleep(duration);
    nodes[idx].classList.remove('highlight');
  }

  async function traverseRecursive(arr, type, idx, stack, result, interval) {
    if (idx >= arr.length || arr[idx] === null) return;
    if (type === 'preorder') {
      stack.push(arr[idx]);
      updateAssist(stack, result);
      await highlightNode(idx, interval);
      log(`访问节点: ${arr[idx]}`);
      result.push(arr[idx]);
      await traverseRecursive(arr, type, 2 * idx + 1, stack, result, interval);
      await traverseRecursive(arr, type, 2 * idx + 2, stack, result, interval);
      stack.pop();
      updateAssist(stack, result);
    } else if (type === 'inorder') {
      stack.push(arr[idx]);
      updateAssist(stack, result);
      await traverseRecursive(arr, type, 2 * idx + 1, stack, result, interval);
      await highlightNode(idx, interval);
      log(`访问节点: ${arr[idx]}`);
      result.push(arr[idx]);
      await traverseRecursive(arr, type, 2 * idx + 2, stack, result, interval);
      stack.pop();
      updateAssist(stack, result);
    } else if (type === 'postorder') {
      stack.push(arr[idx]);
      updateAssist(stack, result);
      await traverseRecursive(arr, type, 2 * idx + 1, stack, result, interval);
      await traverseRecursive(arr, type, 2 * idx + 2, stack, result, interval);
      await highlightNode(idx, interval);
      log(`访问节点: ${arr[idx]}`);
      result.push(arr[idx]);
      stack.pop();
      updateAssist(stack, result);
    } else if (type === 'levelorder') {
      // 递归层级遍历的实现，利用辅助函数访问每层节点
      let height = getTreeHeight(arr);
      for (let level = 0; level < height; level++) {
        await traverseLevel(arr, 0, level, stack, result, interval);
      }
    }
  }

  // 递归辅助函数，访问第 level 层节点
  async function traverseLevel(arr, idx, level, stack, result, interval) {
    if (idx >= arr.length || arr[idx] === null) return;
    if (level === 0) {
      stack.push(arr[idx]);
      updateAssist(stack, result);
      await highlightNode(idx, interval);
      log(`访问节点: ${arr[idx]}`);
      result.push(arr[idx]);
      stack.pop();
      updateAssist(stack, result);
    } else {
      await traverseLevel(arr, 2 * idx + 1, level - 1, stack, result, interval);
      await traverseLevel(arr, 2 * idx + 2, level - 1, stack, result, interval);
    }
  }

  async function traverseIterative(arr, type, interval) {
    let stack = [];
    let result = [];
    if (type === 'preorder') {
      let s = [0];
      while (s.length > 0) {
        let idx = s.pop();
        if (idx >= arr.length || arr[idx] === null) continue;
        stack = [...s];
        stack.push(idx);
        updateAssist(stack.map(i => arr[i]), result);
        await highlightNode(idx, interval);
        log(`访问节点: ${arr[idx]}`);
        result.push(arr[idx]);
        s.push(2 * idx + 2);
        s.push(2 * idx + 1);
      }
    } else if (type === 'inorder') {
      let s = [];
      let idx = 0;
      while (idx < arr.length || s.length > 0) {
        while (idx < arr.length && arr[idx] !== null) {
          s.push(idx);
          updateAssist(s.map(i => arr[i]), result);
          idx = 2 * idx + 1;
          await sleep(interval / 2);
        }
        idx = s.pop();
        await highlightNode(idx, interval);
        log(`访问节点: ${arr[idx]}`);
        result.push(arr[idx]);
        updateAssist(s.map(i => arr[i]), result);
        idx = 2 * idx + 2;
      }
    } else if (type === 'postorder') {
      let s1 = [0], s2 = [];
      while (s1.length > 0) {
        let idx = s1.pop();
        if (idx >= arr.length || arr[idx] === null) continue;
        s2.push(idx);
        s1.push(2 * idx + 1);
        s1.push(2 * idx + 2);
      }
      while (s2.length > 0) {
        let idx = s2.pop();
        updateAssist(s2.map(i => arr[i]), result);
        await highlightNode(idx, interval);
        log(`访问节点: ${arr[idx]}`);
        result.push(arr[idx]);
      }
    } else if (type === 'levelorder') {
      let queue = [0];
      while (queue.length > 0) {
        let idx = queue.shift();
        if (idx >= arr.length || arr[idx] === null) continue;
        updateAssist(queue.map(i => arr[i]), result);
        await highlightNode(idx, interval);
        log(`访问节点: ${arr[idx]}`);
        result.push(arr[idx]);
        queue.push(2 * idx + 1);
        queue.push(2 * idx + 2);
      }
      updateAssist([], result);
    }
  }

  async function start() {
    let input = document.getElementById('treeInput').value.trim();
    let arr;
    try {
      arr = JSON.parse(input);
      if (!Array.isArray(arr)) throw new Error('输入不是数组');
    } catch {
      alert('请输入合法的数组，例如：[1,2,3,null,4]');
      return;
    }
    treeData = arr;
    renderTree(arr);

    document.getElementById('log').innerHTML = '';
    updateAssist([], []);
    let interval = parseInt(document.getElementById('interval').value);
    if (isNaN(interval) || interval < 100) interval = 100;
    const type = document.getElementById('traverseType').value;
    const mode = document.getElementById('mode').value;

    if (mode === 'recursive') {
      await traverseRecursive(arr, type, 0, [], [], interval);
    } else {
      await traverseIterative(arr, type, interval);
    }
  }

  window.onload = () => {
    try {
      const defaultArr = JSON.parse(document.getElementById('treeInput').value);
      renderTree(defaultArr);
    } catch { }
  };
</script>

</body>
</html>