NOIp模拟1 Graph

 1 #include <bits/stdc++.h>
 2 using namespace std;
 3 
 4 struct State {
 5     int next, to;
 6 }e[200005];
 7 
 8 int n, m, u, v, head[100005], cnt, a[100005];
 9 bool vis[100005];
10 
11 void add(int u, int v) {
12     e[++cnt].to=v, e[cnt].next=head[u], head[u]=cnt;
13 }
14 
15 void dfs(int s) {
16     if (vis[s])
17         return;
18     vis[s]=true;
19     for (int i=head[s];i!=-1;i=e[i].next) {
20         dfs(e[i].to);
21         a[s]=max(a[s], max(e[i].to, a[e[i].to]));
22     }
23     return;
24 }
25 
26 int main() {
27     memset(head, -1, sizeof(head));
28     cin >> n >> m;
29     for (int i=1;i<=n;++i)
30         a[i]=i;
31     for (int i=1;i<=m;++i) {
32         scanf("%d %d", &u, &v);
33         add(u, v);
34     }
35     for (int i=1;i<=n;++i)
36         dfs(i);
37     for (int i=1;i<=n;++i)
38         printf("%d ", a[i]);
39 }