wenbao与最短路（spfa）

 1 #include <iostream>
 2 #include <string.h>
 3 #include <queue>
 4 #include <vector>
 5 using namespace std;
 6 const int maxn =  1010;
 7 int n, m, s, t, from, to, val, T[maxn];
 8 bool mark[maxn];
 9 vector<int> a[maxn];
10 vector<int> b[maxn];
11 void spfa(){
12     memset(T, 0x3f, sizeof(T));
13     T[s] = 0;
14     queue<int> q;
15     q.push(s);
16     while(!q.empty()){
17         int k = q.front();
18         q.pop();
19         mark[k] = false;
20         for(int i = 0; i < a[k].size(); i++)if(T[k] + b[k][i] < T[a[k][i]])    {
21             T[a[k][i]] = T[k] + b[k][i];
22             if(!mark[a[k][i]]){
23                 q.push(a[k][i]);
24                 mark[a[k][i]] = true;
25             }
26         }
27     }
28 }
29 int main(){
30     scanf("%d %d %d %d", &n, &m, &s, &t);
31     for(int i = 0; i < m; i++) {
32         scanf("%d %d %d", &from, &to, &val);
33         a[from].push_back(to);
34         b[from].push_back(val);
35         a[to].push_back(from);
36         b[to].push_back(val);
37     }
38     spfa();
39     printf("%d\n", T[t]);
40     return 0;
41 }