218 lines
8.2 KiB
HTML
218 lines
8.2 KiB
HTML
<!DOCTYPE html>
|
||
<html lang="zh-Hans">
|
||
<head>
|
||
<meta charset="UTF-8">
|
||
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
||
<title>048. 路径总和 III – 图解</title>
|
||
<link rel="stylesheet" href="../shared/style.css">
|
||
<style>
|
||
/* page-specific overrides */
|
||
.vis-area { min-height: 120px; padding: 16px 0; }
|
||
.code-section { margin-top: 16px; }
|
||
</style>
|
||
</head>
|
||
<body>
|
||
<div class="container">
|
||
<h1>🟡 048. 路径总和 III <span class="badge medium">中等</span></h1>
|
||
<p class="subtitle">分类：二叉树 ｜ LeetCode Hot 100</p>
|
||
|
||
<!-- 控制面板 -->
|
||
<div class="controls" id="controls">
|
||
<label for="inputArea">输入：</label>
|
||
<input type="text" id="inputArea" placeholder="默认示例，可自定义">
|
||
<button id="applyBtn" class="primary">生成图解</button>
|
||
<select id="exampleSelect"></select>
|
||
<span style="flex:1"></span>
|
||
<button id="prevBtn">◀ 上一步</button>
|
||
<button id="nextBtn">下一步 ▶</button>
|
||
<button id="jumpBtn">⏭ 跳到结果</button>
|
||
<button id="autoBtn">自动播放</button>
|
||
<button id="resetBtn">重置</button>
|
||
</div>
|
||
|
||
<!-- 步骤流水线 -->
|
||
<div class="pipeline" id="pipeline"></div>
|
||
|
||
<!-- 提示条 -->
|
||
<div class="hint info" id="hintBox">
|
||
<span id="stepInfo"></span><br>
|
||
<span id="hintText"></span>
|
||
</div>
|
||
|
||
<!-- 可视化面板 -->
|
||
<div class="panels">
|
||
<div class="panel" id="mainPanel">
|
||
<h3>📊 可视化</h3>
|
||
<div class="vis-area" id="vizArea">点击「生成图解」开始</div>
|
||
</div>
|
||
<div class="panel-grid">
|
||
<div class="panel" id="detailPanel">
|
||
<h3>📝 当前步骤详情</h3>
|
||
<div id="detailContent">等待开始...</div>
|
||
</div>
|
||
<div class="panel" id="resultPanel">
|
||
<h3>✅ 结果</h3>
|
||
<div id="resultContent">等待完成...</div>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
|
||
<!-- 代码 -->
|
||
<div class="panel code-section">
|
||
<h3>💻 参考代码（Python）</h3>
|
||
<div id="codeArea"></div>
|
||
</div>
|
||
|
||
<footer>Powered by QwenPaw · 图解算法 · LeetCode Hot 100</footer>
|
||
</div>
|
||
|
||
<script src="../shared/algo-viz.js"></script>
|
||
<script>
|
||
"use strict";
|
||
(function() {
|
||
// ========== Algorithm Logic ==========
|
||
|
||
function arrayToTree(arr) {
|
||
if (!arr || arr.length === 0) return null;
|
||
let idCtr = 0;
|
||
const nodes = arr.map(v => v === null ? null : {val: v, left: null, right: null, _id: 'n' + (idCtr++)});
|
||
for (let i = 0; i < nodes.length; i++) {
|
||
if (!nodes[i]) continue;
|
||
const li = 2*i+1, ri = 2*i+2;
|
||
if (li < nodes.length) nodes[i].left = nodes[li];
|
||
if (ri < nodes.length) nodes[i].right = nodes[ri];
|
||
}
|
||
return nodes[0];
|
||
}
|
||
function treeToArray(root) {
|
||
if (!root) return [];
|
||
const res = [], q = [root];
|
||
while (q.length) {
|
||
const n = q.shift();
|
||
if (n === null) { res.push(null); continue; }
|
||
res.push(n.val); q.push(n.left, n.right);
|
||
}
|
||
while (res.length && res[res.length-1] === null) res.pop();
|
||
return res;
|
||
}
|
||
function deepClone(node) {
|
||
if (!node) return null;
|
||
return {val: node.val, _id: node._id, left: deepClone(node.left), right: deepClone(node.right)};
|
||
}
|
||
|
||
const examples = [
|
||
{tree: [10,5,-3,3,2,null,11,3,-2,null,1], target: 8, label: '示例1: target=8 → 3'},
|
||
{tree: [5,4,8,11,null,13,4,7,2,null,null,5,1], target: 22, label: '示例2: target=22 → 3'},
|
||
];
|
||
let root, steps, stepCtrl;
|
||
|
||
function buildSteps(arr, target) {
|
||
root = arrayToTree(arr);
|
||
steps = [];
|
||
let count = 0;
|
||
const prefixSum = {0: 1};
|
||
|
||
steps.push({stage:'init', hl:{}, msg:`前缀和 DFS，targetSum=${target}，初始 {0:1}`, prefixSum:{0:1}, currentSum:0, count:0, path:[]});
|
||
|
||
function dfs(node, currSum, path) {
|
||
if (!node) return;
|
||
currSum += node.val;
|
||
path.push(node.val);
|
||
const need = currSum - target;
|
||
const found = prefixSum[need] || 0;
|
||
|
||
if (found > 0) {
|
||
count += found;
|
||
steps.push({stage:'found', hl:{[node._id]:'current'}, msg:`节点 ${node.val}：前缀和=${currSum}，需 ${currSum}-${target}=${need}，出现 ${found} 次，+${found}=${count}`, prefixSum:JSON.parse(JSON.stringify(prefixSum)), currentSum:currSum, count, path:[...path]});
|
||
} else {
|
||
steps.push({stage:'visit', hl:{[node._id]:'active'}, msg:`节点 ${node.val}：前缀和=${currSum}，需 ${need}，未出现`, prefixSum:JSON.parse(JSON.stringify(prefixSum)), currentSum:currSum, count, path:[...path]});
|
||
}
|
||
|
||
prefixSum[currSum] = (prefixSum[currSum] || 0) + 1;
|
||
steps.push({stage:'add_prefix', hl:{[node._id]:'visited'}, msg:`前缀和 ${currSum} 计数+1`, prefixSum:JSON.parse(JSON.stringify(prefixSum)), currentSum:currSum, count, path:[...path]});
|
||
|
||
dfs(node.left, currSum, path);
|
||
dfs(node.right, currSum, path);
|
||
|
||
prefixSum[currSum]--;
|
||
if (prefixSum[currSum] === 0) delete prefixSum[currSum];
|
||
path.pop();
|
||
}
|
||
dfs(root, 0, []);
|
||
steps.push({stage:'done', hl:{}, msg:`满足条件的路径数 = ${count}`, prefixSum:{}, currentSum:0, count, path:[]});
|
||
}
|
||
|
||
function render(step) {
|
||
const s = steps[step];
|
||
let viz = renderBinaryTree(root, {highlights: s.hl});
|
||
if (s.path.length > 0) {
|
||
viz += '<div style="margin-top:8px;"><b>路径：</b>' + s.path.join(' → ') + ` 前缀和=${s.currentSum}</div>`;
|
||
}
|
||
let psHtml = '<div style="margin-top:8px;"><b>前缀和：</b>';
|
||
Object.entries(s.prefixSum).forEach(([k,v]) => { psHtml += `<code>${k}:${v}</code> `; });
|
||
psHtml += '</div>';
|
||
viz += psHtml;
|
||
$('vizArea').innerHTML = viz;
|
||
$('detailContent').innerHTML = '<div class="calc-block">' + s.msg + '</div>';
|
||
if (s.count > 0) {
|
||
$('detailContent').innerHTML += `<div class="current-answer">路径总数：<b>${s.count}</b></div>`;
|
||
}
|
||
if (s.stage === 'done') {
|
||
$('resultContent').innerHTML = `<div class="final-answer">路径总和 III = <b>${s.count}</b> 条</div>`;
|
||
}
|
||
$('hintText').textContent = s.msg;
|
||
const stages = ['init→初始化','visit→访问','found→找到','add_prefix→加前缀和','done→完成'];
|
||
$('pipeline').innerHTML = stages.map(st => {
|
||
const [k,l] = st.split('→');
|
||
return `<span class="pipe-step ${s.stage===k?'active':''}">${l}</span>`;
|
||
}).join('<i>→</i>');
|
||
}
|
||
|
||
function init() {
|
||
const sel = $('exampleSelect');
|
||
examples.forEach((e,i) => { sel.innerHTML += `<option value="${i}">${e.label}</option>`; });
|
||
$('inputArea').value = '[10,5,-3,3,2,null,11,3,-2,null,1], target=8';
|
||
buildSteps(examples[0].tree, examples[0].target);
|
||
stepCtrl = new StepController({onStep: render});
|
||
stepCtrl.setSteps(steps.map((_,i)=>i));
|
||
$('stepInfo').textContent = '步骤 1 / ' + steps.length;
|
||
stepCtrl.onStep = (idx) => { render(idx); $('stepInfo').textContent = `步骤 ${idx+1} / ${steps.length}`; };
|
||
$('applyBtn').onclick = () => {
|
||
const m = $('inputArea').value.match(/\[([^\]]+)\].*target\s*=\s*(-?\d+)/);
|
||
if (!m) { alert('格式: [10,5,-3,...], target=8'); return; }
|
||
const arr = JSON.parse('['+m[1]+']'); const t = parseInt(m[2]);
|
||
buildSteps(arr, t); stepCtrl.setSteps(steps.map((_,i)=>i)); render(0); $('stepInfo').textContent = '步骤 1 / ' + steps.length;
|
||
};
|
||
$('exampleSelect').onchange = () => {
|
||
const e = examples[parseInt($('exampleSelect').value)];
|
||
$('inputArea').value = JSON.stringify(e.tree) + ', target=' + e.target;
|
||
buildSteps(e.tree, e.target); stepCtrl.setSteps(steps.map((_,i)=>i)); render(0);
|
||
};
|
||
$('prevBtn').onclick = () => stepCtrl.prev();
|
||
$('nextBtn').onclick = () => stepCtrl.next();
|
||
$('jumpBtn').onclick = () => stepCtrl.jumpToEnd();
|
||
$('autoBtn').onclick = () => { const on = stepCtrl.toggleAuto(); $('autoBtn').textContent = on ? '暂停' : '自动播放'; };
|
||
$('resetBtn').onclick = () => { stepCtrl.reset(); $('autoBtn').textContent = '自动播放'; };
|
||
}
|
||
init();
|
||
$('codeArea').innerHTML = renderCode(`def pathSum(root, targetSum):
|
||
from collections import defaultdict
|
||
prefix = defaultdict(int)
|
||
prefix[0] = 1
|
||
count = 0
|
||
def dfs(node, curr):
|
||
nonlocal count
|
||
if not node: return
|
||
curr += node.val
|
||
count += prefix[curr - targetSum]
|
||
prefix[curr] += 1
|
||
dfs(node.left, curr)
|
||
dfs(node.right, curr)
|
||
prefix[curr] -= 1
|
||
dfs(root, 0)
|
||
return count`, {lang:'Python'});
|
||
|
||
})();
|
||
</script>
|
||
</body>
|
||
</html> |