[ An Ac a Day ^_^ ] [kuangbin带你飞]专题四 最短路练习 POJ 2387 Til the Cows Come Home

求1到N的最短路

注意有重边 跑一遍dijkstra就行

 /* ***********************************************
 Author        :Sun Yuefeng
 Created Time  :2016/10/22 14:18:06
 File Name     :A.cpp
 ************************************************ */

 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 #include<cmath>
 #include<cstring>
 #include<string>
 #include<bitset>
 #include<map>
 #include<set>
 #include<stack>
 #include<vector>
 #include<queue>
 #include<list>
 #define M(a,b) memset(a,b,sizeof(a))
 using namespace std;
 typedef long long ll;
 const int inf=0x3f3f3f3f;
 const int maxn=1e3+;
 const int mod=1e7+;
 int dx[]= {,,,-,,-,,-};
 int dy[]= {,-,,,-,,,-};

 int n,m;
 int way[maxn][maxn];
 int dis[maxn];
 bool vis[maxn];

 void dijkstra(int x){
     for(int i=;i<=m;i++){
         dis[i]=inf;
         vis[i]=false;
     }
     dis[x]=;
     for(int i=;i<=m;i++){
         int k=-;
         int min=inf;
         for(int j=;j<=m;j++){
             if(!vis[j]&&dis[j]<min){
                 min=dis[j];
                 k=j;
             }
         }
         if(k==-) break;
         vis[k]=true;
         for(int j=;j<=m;j++){
             if(!vis[j]&&dis[j]>dis[k]+way[j][k]){
                 dis[j]=dis[k]+way[j][k];
             }
         }
     }
 }

 int main()
 {
     //freopen("in.txt","r",stdin);
     //freopen("out.txt","w",stdout);
     while(~scanf("%d%d",&n,&m)){
         int a,b,v;
         M(way,inf);
         for(int i=;i<n;i++){
             scanf("%d%d%d",&a,&b,&v);
             if(way[a][b]>v){
                 way[a][b]=v;
                 way[b][a]=v;
             }
         }
         dijkstra();
         int min=inf;
         printf("%d\n",dis[m]);
     }
     return ;
 }