LightOJ 1002 Country Roads

来源：互联网发布：淘宝儿童玩具大全编辑：程序博客网时间：2024/06/05 21:24

题意：给一个图，再给个点p，求其它各点到点p的距离

裸的单源最短路，新手专用

#include <bits/stdc++.h>using namespace std;const int INF = 1e9;int n;bool vis[505];int dis[505];int g[505][505];void spfa(int s){    for(int i = 0; i < n; i++)        dis[i] = INF, vis[i] = false;    queue<int> q;    dis[s] = 0; vis[s] = true; q.push(s);    while(!q.empty())    {        int p = q.front(); q.pop(); vis[p] = false;        for(int i = 0; i < n; i++)        {            if(dis[i] <= max(dis[p], g[p][i])) continue;            dis[i] = max(dis[p], g[p][i]);            if(vis[i]) continue;            vis[i] = true; q.push(i);        }    }}int main(){    int T;    scanf("%d", &T);    for(int ca = 1; ca <= T; ca++)    {        int m;        scanf("%d%d", &n, &m);        for(int i = 0; i < n; i++)            for(int j = 0; j < n; j++)                g[i][j] = INF;        for(int i = 0; i < m; i++)        {            int l, r, v;            scanf("%d%d%d", &l, &r, &v);            g[l][r] = g[r][l] = min(g[l][r], v);        }        int aim;        scanf("%d", &aim);        spfa(aim);        printf("Case %d:\n", ca);        for(int i = 0; i < n; i++)        {            if(dis[i] != INF) printf("%d\n", dis[i]);            else printf("Impossible\n");        }    }    return 0;}

1 0