197 lines
8.5 KiB
HTML
197 lines
8.5 KiB
HTML
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<!DOCTYPE html>
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<html lang="zh-Hans">
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<head>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>029. 删除链表的倒数第 N 个结点 – 图解</title>
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<link rel="stylesheet" href="../shared/style.css">
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<style>
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/* page-specific overrides */
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.vis-area { min-height: 120px; padding: 16px 0; }
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.code-section { margin-top: 16px; }
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</style>
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</head>
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<body>
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<div class="container">
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<h1>🟡 029. 删除链表的倒数第 N 个结点 <span class="badge medium">中等</span></h1>
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<p class="subtitle">分类：链表 ｜ LeetCode Hot 100</p>
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<!-- 控制面板 -->
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<div class="controls" id="controls">
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<label for="inputArea">输入：</label>
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<input type="text" id="inputArea" placeholder="默认示例，可自定义">
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<button id="applyBtn" class="primary">生成图解</button>
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<select id="exampleSelect"></select>
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<span style="flex:1"></span>
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<button id="prevBtn">◀ 上一步</button>
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<button id="nextBtn">下一步 ▶</button>
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<button id="jumpBtn">⏭ 跳到结果</button>
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<button id="autoBtn">自动播放</button>
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<button id="resetBtn">重置</button>
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</div>
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<!-- 步骤流水线 -->
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<div class="pipeline" id="pipeline"></div>
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<!-- 提示条 -->
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<div class="hint info" id="hintBox">
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<span id="stepInfo"></span><br>
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<span id="hintText"></span>
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</div>
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<!-- 可视化面板 -->
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<div class="panels">
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<div class="panel" id="mainPanel">
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<h3>📊 可视化</h3>
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<div class="vis-area" id="vizArea">点击「生成图解」开始</div>
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</div>
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<div class="panel-grid">
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<div class="panel" id="detailPanel">
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<h3>📝 当前步骤详情</h3>
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<div id="detailContent">等待开始...</div>
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</div>
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<div class="panel" id="resultPanel">
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<h3>✅ 结果</h3>
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<div id="resultContent">等待完成...</div>
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</div>
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</div>
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</div>
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<!-- 代码 -->
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<div class="panel code-section">
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<h3>💻 参考代码（Python）</h3>
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<div id="codeArea"></div>
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</div>
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<footer>Powered by QwenPaw · 图解算法 · LeetCode Hot 100</footer>
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</div>
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<script src="../shared/algo-viz.js"></script>
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<script>
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"use strict";
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(function() {
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// ========== Algorithm Logic ==========
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function llViz(nodes, opts) {
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opts = opts || {};
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var highs = opts.highs || {};
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var ptrs = opts.ptrs || {};
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var cycle = opts.cycle != null ? opts.cycle : -1;
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var label = opts.label || '';
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var showNull = opts.showNull !== false;
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var html = '';
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if (label) html += '<div style="font-size:13px;font-weight:600;color:var(--text-secondary);margin-bottom:4px;">' + label + '</div>';
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html += '<div style="display:flex;flex-wrap:wrap;align-items:center;gap:4px;padding:4px 0;">';
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for (var i = 0; i < nodes.length; i++) {
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var cls = highs[i] || '';
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html += '<div style="position:relative;display:inline-flex;flex-direction:column;align-items:center;">';
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html += '<div class="ll-node ' + cls + '">';
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html += '<span class="val">' + nodes[i] + '</span>';
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if (i === cycle) {
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html += '<span class="arrow" style="color:var(--red);font-weight:bold;">↩</span>';
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} else if (i < nodes.length - 1) {
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html += '<span class="arrow">→</span>';
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} else if (showNull && i === nodes.length - 1) {
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html += '<span class="arrow" style="color:var(--text-muted);">∅</span>';
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}
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html += '</div>';
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var plabels = [];
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var pkeys = Object.keys(ptrs);
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for (var pi = 0; pi < pkeys.length; pi++) {
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if (ptrs[pkeys[pi]] === i) plabels.push(pkeys[pi]);
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}
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if (plabels.length) {
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html += '<div style="font-size:10px;font-weight:700;color:var(--blue);margin-top:2px;white-space:nowrap;">' + plabels.join(',') + '</div>';
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}
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html += '</div>';
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}
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html += '</div>';
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return html;
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}
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function setPipeline(stages, current) {
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$('pipeline').innerHTML = stages.map(function(st) {
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var parts = st.split('\u2192');
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return '<span class="pipe-step ' + (current===parts[0]?'active':'') + '">' + parts[1] + '</span>';
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}).join('<i>\u2192</i>');
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}
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var examples = [
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{input:[1,2,3,4,5], n:2, label:'示例1: [1,2,3,4,5] n=2 删除4'},
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{input:[1], n:1, label:'示例2: [1] n=1 删除1'},
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{input:[1,2], n:1, label:'示例3: [1,2] n=1 删除2'},
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];
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var nodes, steps, stepCtrl;
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function buildSteps(ex) {
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nodes = ex.input.slice(); steps = [];
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var n = ex.n;
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var len = nodes.length;
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steps.push({stage:'init', msg:'快慢指针：fast 先走 n 步，然后 slow 和 fast 同步走', slow:-1, fast:0, phase:'advance'});
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// Use dummy node represented as index -1
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var slow = -1, fast = 0;
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// fast advances n steps
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for (var i = 0; i < n; i++) {
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steps.push({stage:'advance', msg:'fast 前进：' + (i+1) + '/' + n + ' 步，fast=' + (fast < len ? nodes[fast] : 'null'), slow:-1, fast:fast, phase:'advance'});
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fast++;
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}
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steps.push({stage:'ready', msg:'fast 已领先 ' + n + ' 步，现在 slow 和 fast 同步前进', slow:-1, fast:fast, phase:'move'});
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// both advance until fast reaches end
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while (fast < len) {
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slow++;
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if (fast < len) fast++;
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steps.push({stage:'move', msg:'slow→' + (slow>=0?nodes[slow]:'dummy') + ', fast→' + (fast<len?nodes[fast]:'null'), slow:slow, fast:fast, phase:'move'});
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}
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// slow.next is the node to delete
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var delIdx = slow + 1;
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steps.push({stage:'delete', msg:'删除 slow.next = 节点 ' + nodes[delIdx] + ' (index ' + delIdx + ')', slow:slow, fast:fast, delIdx:delIdx, phase:'delete'});
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var result = nodes.slice();
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result.splice(delIdx, 1);
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steps.push({stage:'done', msg:'删除后结果：[' + result.join(',') + ']', result:result, phase:'done'});
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}
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function render(step) {
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var s = steps[step];
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var hl = {};
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var ptrs = {};
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if (s.slow >= 0 && s.slow < nodes.length) { hl[s.slow] = 'active'; ptrs.slow = s.slow; }
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if (s.fast >= 0 && s.fast < nodes.length) { hl[s.fast] = 'current'; ptrs.fast = s.fast; }
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if (s.delIdx !== undefined && s.delIdx < nodes.length) hl[s.delIdx] = 'null-node';
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var vizLabel = '链表 (n=' + examples[parseInt($('exampleSelect').value)||0].n + ')';
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var viz = llViz(nodes, {highs:hl, ptrs:ptrs, label:vizLabel});
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if (s.slow === -1 && (s.phase === 'advance' || s.phase === 'ready')) {
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viz += '<div style="font-size:12px;color:var(--text-muted);">slow 在 dummy 节点</div>';
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}
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$('vizArea').innerHTML = viz;
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$('detailContent').innerHTML = '<div class="calc-block">' + s.msg + '</div>';
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if (s.stage === 'done') {
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$('resultContent').innerHTML = '<div class="final-answer">删除后：<b>[' + s.result.join(' → ') + ']</b></div>';
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}
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$('hintText').textContent = s.msg;
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setPipeline(['init\u2192初始化','advance\u2192快进','ready\u2192就绪','move\u2192同步','delete\u2192删除','done\u2192完成'], s.stage);
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}
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function init() {
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var sel = $('exampleSelect');
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examples.forEach(function(e,i){ sel.innerHTML += '<option value="'+i+'">'+e.label+'</option>'; });
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$('inputArea').value = '[1,2,3,4,5] n=2';
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buildSteps(examples[0]);
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stepCtrl = new StepController({onStep:render});
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stepCtrl.setSteps(steps.map(function(_,i){return i;}));
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$('stepInfo').textContent = '步骤 1 / ' + steps.length;
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stepCtrl.onStep = function(idx){ render(idx); $('stepInfo').textContent = '步骤 '+(idx+1)+' / '+steps.length; };
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$('applyBtn').onclick = function(){ buildSteps(examples[parseInt($('exampleSelect').value)]); stepCtrl.setSteps(steps.map(function(_,i){return i;})); render(0); };
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$('exampleSelect').onchange = function(){ buildSteps(examples[parseInt($('exampleSelect').value)]); stepCtrl.setSteps(steps.map(function(_,i){return i;})); render(0); };
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$('prevBtn').onclick = function(){ stepCtrl.prev(); };
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$('nextBtn').onclick = function(){ stepCtrl.next(); };
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$('jumpBtn').onclick = function(){ stepCtrl.jumpToEnd(); };
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$('autoBtn').onclick = function(){ var on=stepCtrl.toggleAuto(); $('autoBtn').textContent=on?'暂停':'自动播放'; };
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$('resetBtn').onclick = function(){ stepCtrl.reset(); $('autoBtn').textContent='自动播放'; };
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}
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init();
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$('codeArea').innerHTML = renderCode('def removeNthFromEnd(head, n):\n dummy = ListNode(0, head)\n fast = slow = dummy\n for _ in range(n):\n fast = fast.next\n while fast.next:\n slow = slow.next\n fast = fast.next\n slow.next = slow.next.next\n return dummy.next', {lang:'Python'});
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})();
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</script>
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</body>
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</html>
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