1379：热浪(heatwv)

热浪

#include<iostream>
#include<cstring>
#include<cmath>
#define inf 0x3f3f3f3f
using namespace std;

const int N=2505;
int mapp[N][N],dis[N];
bool vis[N];

int main(){
    int n,m,s,e;
    cin>>n>>m>>s>>e;
    memset(mapp,inf,sizeof(mapp));
    while(m--){
        int a,b,c;
        scanf("%d%d%d",&a,&b,&c);
        mapp[a][b]=mapp[b][a]=c;
    }
    for(int i=1;i<=n;i++)
        dis[i]=mapp[s][i];
    memset(vis,false,sizeof(vis));
    dis[s]=0,vis[s]=true;
    for(int i=1;i<n;i++){
        int minn=inf;
        int k=0;
        for(int j=1;j<=n;j++){
            if(!vis[j]&&minn>dis[j]){
                minn=dis[j];
                k=j;
            }            
        }
        if(!k)break;
        vis[k]=true;
        for(int j=1;j<=n;j++)
            dis[j]=min(dis[j],dis[k]+mapp[k][j]);
    }
    cout<<dis[e];
    return 0;
}