朴素dijkstra

#include <bits/stdc++.h>
using namespace std;

const int N = 550, M = 10010;
int g[N][N], dist[N];
bool st[N];
int m, n;

int dijkstra() {
    memset(dist,0x3f,sizeof dist);
    dist[1] = 0;
    for(int i = 0; i < n; i++) { // 循环n次 更新最短路径
        int t = -1;
        for(int j = 1; j <= n; j++) { // 找到最小的dist[j]
            if(!st[j] && (t == -1 || dist[t] > dist[j])) {
                t = j;
            }
        }
        st[t] = true;
        for(int j = 1; j <= n; j++) { // 用最短的这个来更新其他路径
            dist[j] = min(dist[j], dist[t] + g[t][j]);
        }
    }
    if(dist[n] == 0x3f3f3f3f) return -1;
    return dist[n];
}

int main() {
    scanf("%d%d",&n,&m);
    memset(g,0x3f,sizeof g);
    while(m -- ) {
        int a, b, c;
        scanf("%d%d%d",&a,&b,&c);
        g[a][b] = min(g[a][b],c);
    }
    int t = dijkstra();
    printf("%d\n",t);
    return 0;
}