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<div style="padding:40px;color:#cbccc6"><h1>欧拉路径 (Königsberg)</h1><p>七桥问题：奇度顶点 4 个 → 无解。</p><div style="padding:20px;background:#0d1017;border-left:3px solid #ffb454"><span class="katex-display"><span class="katex"><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8304em;vertical-align:-0.136em;"></span><span class="mord text"><span class="mord">exists iff </span></span><span class="mspace" style="margin-right:0.2778em;"></span><span class="mrel">≤</span><span class="mspace" style="margin-right:0.2778em;"></span></span><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord">2</span><span class="mord text"><span class="mord"> odd-degree vertices</span></span></span></span></span></span></div><p style="color:#707a8c">该页面需要 JavaScript 进行交互式可视化。</p></div>
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