lessons/课程/插图/02-强连通与双连通/00-圆方树-02-边栈与封口.svg

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  <rect width="940" height="360" fill="#f8fafc"/><text x="35" y="34" class="t" font-weight="bold">边栈：一段 DFS 子树再也绕不到父亲上方时，整批走廊结账</text>
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  <g class="t" text-anchor="middle"><text x="120" y="96">A</text><text x="230" y="166">C</text><text x="340" y="241">F</text><text x="445" y="311">G</text><text x="340" y="91">D</text><text x="445" y="161">E</text></g>
  <text x="56" y="340" class="s">蓝实线＝树边；橙虚线＝返祖边。F-G 没有虚线旁路，先封成一个块。</text>
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  <text x="580" y="84" class="t" font-weight="bold">栈顶</text>
  <rect x="580" y="102" width="250" height="42" rx="7" class="card"/><text x="598" y="129" class="t">F-G</text><text x="705" y="129" class="s">low[G] &gt; dfn[F]</text>
  <rect x="580" y="150" width="250" height="42" rx="7" class="card"/><text x="598" y="177" class="t">C-F</text><text x="705" y="177" class="s">随后 low[F] &gt; dfn[C]</text>
  <rect x="580" y="198" width="250" height="42" rx="7" class="stack"/><text x="598" y="225" class="t">C-D, D-E, E-C</text><text x="598" y="258" class="s">low[D] = dfn[C]，三角形一起弹出</text>
  <text x="580" y="305" class="s">每条边只进栈、出栈一次；方点就在一次弹栈时出生。</text>
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