洛谷 P1364 医院设置

题目传送门

解题思路:

先Floyd一遍,求出每个点到其他任意一个点的距离,再暴力更新以每个点为源点的最短路.这题数据范围好水

AC代码:

#include<cstdio>
#include<iostream>
#include<cstring>

using namespace std;

int n,a[101],dist[101][101],sum[101],ans = 0x7f7f7f7f; 

int main()
{
    memset(dist,100000007,sizeof(dist));
    scanf("%d",&n);
    for(int i = 1;i <= n; i++) {
        int x,y;
        scanf("%d%d%d",&a[i],&x,&y);
        dist[i][i] = 0;
        if(x != 0) dist[x][i] = dist[i][x] = 1;
        if(y != 0) dist[i][y] = dist[y][i] = 1;
    }
    for(int k = 1;k <= n; k++)
        for(int i = 1;i <= n; i++)
            if(i != k)
                for(int j = 1;j <= n; j++) 
                    if(i != j && j != k)
                        dist[i][j] = min(dist[i][k] + dist[k][j],dist[i][j]);
    for(int i = 1;i <= n; i++) {
        for(int j = 1;j <= n; j++) 
            if(i != j) 
                sum[i] = sum[i] + a[j] * dist[i][j]; 
        ans = min(ans,sum[i]);
    }    
    printf("%d",ans);        
    return 0;
}