最短路(模板)

 1 //dijkstra
 2 void dij(int s){
 3     priority_queue <pair <int,int> > q; //小根堆 
 4     while(!q.empty()) q.pop();
 5     q.push(make_pair(0,s));
 6     while(!q.empty()){
 7         int u = q.top().second;
 8         q.pop();
 9         if(vis[u]) continue;
10         vis[u] = 1;
11         for(int i = head[u];i;i = nxt[i]){
12             int t = edge[i].tt,v = edge[i].vv;
13             if(dis[t] > dis[u] + v){
14                 dis[t] = dis[u] + v;
15                 q.push(make_pair(dis[t],t));
16             }
17         }
18     }
19     return;
20 }
21 //floyd
22 void floyd(int s,int t){  //s:起点,t:终点 
23     for(int k = 1;k <= n;++ k){
24         for(int i = 1;i <= n;++ i){
25             for(int j = 1;j <= n;++ j){
26                 f[i][j] = min(f[i][j],f[i][k] + f[k][j]);
27             }
28         }
29     }
30     cout << f[s][t] << ‘\n‘;
31     return;
32 }
33 //spfa
34 queue <int> s;
35 void spfa(int x){//x:起点 
36     memset(dis,0x3f,sizeof(dis));
37     while(!s.empty()) s.pop();
38     dis[x] = 0;
39     s.push(x);
40     vis[x] = 1;
41     while(!s.empty()){
42         int u = s.front();
43         s.pop();
44         vis[u] = 0;
45         for(int i = head[u];i;i = nxt[i]){
46             int t = edge[i].tt,v = edge[i].vv;
47             if(dis[t] > dis[u] + v){
48                 dis[t] = dis[u] + v;
49                 if(!vis[t]){
50                     s.push(t);
51                     vis[t] = 1;
52                 }
53             }
54         }
55     }
56     return;
57 }