最短路径之Bellman-Ford算法
第一行为源点个数，边的个数m
接下来m行为a->b和权值
5 5
2 3 2
1 2 -3
1 5 5
4 5 2
3 4 3
Bellman-Ford算法（1）：
1 #include<iostream> 2 #include<cstdio> 3 #include<algorithm> 4 #define inf 1000000000 5 using namespace std; 6 int main() 7 { 8 int dis[100], u[100], v[100], w[100]; 9 int n, m; 10 cin >> n >> m; 11 for (int i = 1; i <= m; i++) 12 cin >> u[i] >> v[i] >> w[i]; 13 for (int i = 1; i <= n; i++) 14 dis[i] = inf; 15 dis[1] = 0; 16 for (int k = 1; k < n; k++) 17 for (int i = 1; i <= m; i++) 18 dis[v[i]] = min(dis[v[i]], dis[u[i]] + w[i]); 19 for (int i = 1; i <= n; i++) 20 cout << dis[i] << " "; 21 return 0; 22 }
（2）
1 #include<iostream> 2 #include<queue> 3 #include<algorithm> 4 using namespace std; 5 #define inf 1000000000 6 struct edge 7 { 8 int from, to, cost; 9 }; 10 edge es[10000]; 11 int d[100], V, E; 12 void path(int s) 13 { 14 for (int i = 0; i <= V; i++) d[i] = inf; 15 d[s] = 0; 16 while (true) 17 { 18 bool update = false; 19 for (int i = 0; i < E; i++) 20 { 21 edge e = es[i]; 22 if (d[e.from] != inf&& d[e.to]>d[e.from] + e.cost) 23 { 24 d[e.to] = d[e.from] + e.cost; 25 update = true; 26 } 28 } 29 if (!update) break; 30 } 31 for (int i = 1; i <= V; i++) 32 cout << d[i] << " "; 33 } 34 int main() 35 { 36 cin >> V >> E; 37 for (int i = 0; i < E; i++) 38 { 39 cin >> es[i].from >> es[i].to >> es[i].cost; 40 } 41 path(1); 42 return 0; 43 }
