从 s 点到 t 点的最短路（简单模板）(迪杰斯特拉）

迪杰斯特拉简单版

#include <bits/stdc++.h>

using namespace std;

int m,n;
const int inf = 0x3f3f3f3f;
int dis[1005];
int gra[405][405];
int vis[1005];
void dj(int s, int t)
{
    memset(vis,0,sizeof(vis));
    int minn, v;
    for(int i = 0; i < n; i ++)
        dis[i] = gra[s][i];
    for(int i = 1; i <= n; i ++)
    {
        minn = inf;
        for(int j = 0; j < n; j ++)
        {
            if(!vis[j] && dis[j] < minn)
            {
                v = j;
                minn = dis[j];
            }
        }
        vis[v] = 1;
        for(int j = 0; j < n; j ++)
        {
            if(gra[v][j] + dis[v] < dis[j] && !vis[j])
            {
                dis[j] = gra[v][j] + dis[v];
            }
        }
    }
    if(dis[t] == inf)printf("-1\n");
    else printf("%d\n",dis[t]);
}
int main()
{
    int i, j, a, b, c, s, t;
    while(~scanf("%d%d", &n, &m))
    {
        for(i = 0; i < n; i ++)
        {
            for(j = 0; j < n; j ++)
            {
                if(i == j)
                    gra[i][j] = 0;
                else
                    gra[i][j] = gra[j][i] = inf;
            }
        }
        for(i = 1; i <= m; i ++)
        {
            scanf("%d%d%d", &a, &b, &c);
            if(gra[a][b] > c)
                gra[a][b] = gra[b][a] = c;
        }
        scanf("%d %d",&s,&t);
        dj(s,t);
    }
    return 0;
}