poj 2421-Constructing Roads(经典Prime算法)

大致题意是求一颗最小生成树

题目链接：http://poj.org/problem?id=2421

#include<iostream>#include<cstring>#include<algorithm>using namespace std;int main(){int dis[110][110],flag[110],distance;int n,q,i,j,k;while(cin>>n){distance=0;memset(flag,0,sizeof(flag));for(i=1;i<=n;i++){for(j=1;j<=n;j++){cin>>dis[i][j];}}cin>>q;for(i=0;i<q;i++){int a,b;cin>>a>>b;dis[a][b]=0;dis[b][a]=0;}flag[1]=1;int temp;for(k=1;k<n;k++){int min=100000;for(i=1;i<=n;i++){for(j=1;j<=n;j++){if(flag[i]==1&&flag[j]==0){if(min>dis[i][j]){min=dis[i][j];temp=j;}}}}flag[temp]=1;distance+=min;}cout<<distance<<endl;}return 0;}