POJ 2387 Til the Cows Come Home(最短路模板)
题目链接：http://poj.org/problem?id=2387
题意：有n个城市点，m条边，求n到1的最短路径。n<=1000; m<=2000
就是一个标准的最短路模板。
1 #include<iostream> 2 #include<algorithm> 3 #include<cstring> 4 #include<vector> 5 #include<queue> 6 7 using namespace std; 8 const int maxn = 2010; 9 const int INF = 0x3f3f3f3f3f; 10 int n, m; 11 struct node{ 12 int to, cost; 13 node() {} 14 node(int a, int b) :to(a), cost(b) {} 15 }; 16 vector<node> e[maxn]; 17 int vis[maxn], f[maxn], dis[maxn]; 18 void SPFA(int s) 19 { 20 for (int i = 0; i < maxn; i++) { 21 vis[i] = 0; f[i] = 0; 22 dis[i] = INF; 23 } 24 dis[s] = 0; 25 vis[s] = 1; f[s]++; 26 queue<int>Q; 27 Q.push(s); 28 while (!Q.empty()) { 29 int t = Q.front(); Q.pop(); 30 vis[t] = 0; 31 for (int i = 0; i < e[t].size(); i++) { 32 int tmp = e[t][i].to; 33 if (dis[tmp] > dis[t] + e[t][i].cost) { 34 dis[tmp] = dis[t] + e[t][i].cost; 35 if (!vis[tmp]) { 36 vis[tmp] = 1; 37 Q.push(tmp); 38 if (++f[tmp] > n)return; 39 } 40 } 41 } 42 } 43 return; 44 } 45 int main() 46 { 47 ios::sync_with_stdio(false); 48 while (cin >> m >> n) { 49 for (int a, b, c, i = 1; i <= m; i++) { 50 cin >> a >> b >> c; 51 e[a].push_back(node(b, c)); 52 e[b].push_back(node(a, c)); 53 } 54 SPFA(1); 55 cout << dis[n] << endl; 56 } 57 return 0; 58 }
