dijkstra

#include<bits/stdc++.h>
using namespace std;
int f[2005][2005];
int dis[2005];
bool vis[2005];
int n,m;
int main(){
    memset(f,0x3f,sizeof(f));
    for(int i=1;i<=n;i++) f[i][i]=0;
    scanf("%d%d",&n,&m);
    while(m){
        m--;
        int a,b,c;
        scanf("%d%d%d",&a,&b,&c);
        f[a][b]=c;
        f[b][a]=c;
    }
    for(int i=1;i<=n;i++) dis[i]=f[1][i];
    vis[1]=1;
    for(int i=1;i<=n;i++){
        int now=1061109567,k=0;
        for(int j=1;j<=n;j++){
            if(!vis[j]&&dis[j]<now){
                now=dis[j];
                k=j;
            }
        }
        if(!k) break;
        vis[k]=1;
        for(int j=1;j<=n;j++){
            if(!vis[j]&&dis[j]>dis[k]+f[k][j]){
                dis[j]=dis[k]+f[k][j];
            }
        }
    }
    printf("%d",dis[n]);
    return 0;
}