拓扑排序模板

kahn算法优先队列模板

从入度考虑

int indegree[MAXN];int topo[MAXN];int graph[MAXN][MAXN]; //邻接矩阵int index, n;struct cmp1 {bool operator ()(int &a, int &b) {return a>b;//最小值优先}};void toposort(){priority_queue<int,vector<int>,cmp1>q;for (int i = 1; i <= n; i++){if (!indegree[i])q.push(i);}index = 0;while (!q.empty()){int temp= q.top();q.pop();topo[index++] = temp;for (int i = 1; i <= n; i++){if (graph[temp][i]){indegree[i]--;if (!indegree[i])q.push(i);}}}}

DFS 实现

从出度为0考虑

bool dfs(int u){vis[u] = -1;//-1用来表示顶点u正在访问  for (int i = 0; i < graph[u].size(); i++){if (vis[graph[u][i]] == -1)//表示这个点进入了两次，肯定出现了环  return false;else if (vis[graph[u][i]] == 0){if (!dfs(graph[u][i]))return false;}}vis[u] = 1;topo[cnt++] = u;//放到结果数组里，输出的时候记得倒序输出，（回溯的原因）  return true;}bool toposort(int n){memset(vis, 0, sizeof(vis));for (int i = 1; i <= n; i++){if (!vis[i]){if (!dfs(i)) return false;//huan  }}return true;}