题目链接：Dijkstra求最短路 I

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 510;

int n, m;
int g[N][N];
int dist[N];
bool st[N];

int dijkstra()
{
    memset(dist, 0x3f, sizeof dist);
    
    dist[1] = 0;
    for(int i = 0; i < n; i++)
    {
        // t 代表没有确认的最短路长度的最小值
        int t = -1;
        for(int j = 1; j <= n; j ++)
        {
            if(!st[j] && (t == -1 || dist[t] > dist[j]))
            {
                t = j;
            }
        }
        st[t] = true;
        // 更新其他点的距离
        for(int j = 1; j <= n; j++)
        {
            dist[j]  = min(dist[j], dist[t] + g[t][j]);
        }
    }
    if(dist[n] == 0x3f3f3f3f) return -1;
    return dist[n];
}

int main()
{
    cin >> n >> m;
    
    memset(g, 0x3f, sizeof g);
    
    for(int i = 0; i < m; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        g[a][b] = min(g[a][b], c);
    }
    
    cout << dijkstra() << endl;
    
    return 0;
}