文件目录

#include <bits/stdc++.h>
using namespace std;
int n, m, a, b, c, g[2005][2005];
int dis[2005];
bool vis[2005];
void dijk(int s)
{
    memset(dis, 0x3f, sizeof(dis));
    dis[s] = 0;
    while (true)
    {
        int k = 0;
        for (int i = 1; i <= n; i++)
            if (!vis[i] && dis[k] > dis[i])
                k = i;
        if (k == 0)
            break;
        vis[k] = 1;
        for (int i = 1; i <= n; i++)
        {
            if (!vis[i] && dis[i] > dis[k] + g[k][i])
            {
                dis[i] = dis[k] + g[k][i];
            }
        }
    }
}
int main()
{
    memset(g, 0x3f, sizeof(g));
    cin >> n >> m;
    while (m--)
    {
        cin >> a >> b >> c;
        if (g[a][b] > c)
            g[a][b] = g[b][a] = c;
    }
    for (int i = 1; i <= n; i++)
        g[i][i] = 0;
    dijk(1);
    if (dis[n] == dis[0])
        cout << -1;
    else
        cout << dis[n];
    return 0;
}