图上最短路（bellman-ford + queue优化算法）

 1 #include <cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 #include<queue>
 5 #include<vector>
 6 #include<cstring>
 7 #include<algorithm>
 8 using namespace std;
 9 vector<int>v[10005], c[10005];
10 const int INF = 2147483647;
11 int dis[10005];
12 bool vis[10005];
13 void sssp(int a)    //single source shortest path
14 {
15     for(int i = 0; i < 10005; ++i) dis[i] = INF;
16     dis[a] = 0;
17     memset(vis, 0, sizeof(vis));
18     queue<int>q;q.push(a);
19     while(!q.empty())
20     {
21         int now = q.front();q.pop();
22         vis[now] = 0;
23         for(int i = 0; i < (int)v[now].size(); ++i)
24         {
25             if(dis[now] + c[now][i] < dis[v[now][i]])
26             {
27                 dis[v[now][i]] = dis[now] + c[now][i];
28                 if(vis[v[now][i]] == 0)
29                     q.push(v[now][i]); vis[v[now][i]] = 1;
30             }
31         }
32     }
33 }
34 int main()
35 {
36     int n, m, s;
37     scanf("%d%d%d", &n, &m, &s);
38     for(int i = 0; i < m; ++i)
39     {
40         int f, g, w;
41         scanf("%d%d%d", &f, &g, &w);
42         v[f].push_back(g);c[f].push_back(w);    
43     }
44     sssp(s);
45     for (int i = 1; i <= n; i++){
46         printf("%d%c", dis[i], i == n ? ‘\n‘ : ‘ ‘);
47     }
48 }