Unverified Commit 520d0825 authored by ZHB's avatar ZHB Committed by GitHub
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修改 DFS 版拓扑排序的代码 

1. 修正代码中的错误
2. 改用 vector 存图
3. 节点编号的范围改为 [0, n)
parent e592b8eb

docs/graph/topo.md

+14 −9
Original line number Diff line number Diff line
@@ -84,26 +84,31 @@ bool toposort() { 
## DFS 算法



```cpp

// dfs 版本

vector<int> G[MAXN]; // vector 实现的邻接表

int c[MAXN];         // 标志数组

vector<int> topo;    // 拓扑排序后的节点



bool dfs(int u) {

  c[u] = -1;

  for (int v = 0; v <= n; v++)

    if (G[u][v]) {

  for (int v : G[u]) {

    if (c[v] < 0)

      return false;

    else if (!c[v])

        dfs(v);

      if (!dfs(v))

        return false;

  }

  c[u] = 1;

  topo.push_back(u);

  return true;

}



bool toposort() {

  topo.clear();

  memset(c, 0, sizeof(c));

  for (int u = 0; u <= n; u++)

  for (int u = 0; u < n; u++)

    if (!c[u])

      if (!dfs(u)) return false;

      if (!dfs(u))

        return false;

  reverse(topo.begin(), topo.end());

  return true;

}