POJ 2421 Constructing Roads

#include <stdio.h>
#include <iostream>
#include <string.h>
using namespace std;

#define inf 0x3f3f3f3f
int N, P;
int mp[110][110];
bool vis[110];
int dis[110];

int prim() {
    memset(dis, inf, sizeof(dis));
    memset(vis, false, sizeof(vis));

    dis[1] = 0;
    int temp;
    int res = 0;
    for(int i = 1; i <= N; i ++)
        dis[i] = mp[1][i];

    for(int i = 1; i <= N; i ++) {
        int minn = inf;
        for(int j = 1; j <= N; j ++) {
            if(!vis[j] && dis[j] < minn) {
                temp = j;
                minn = dis[j];
            }
        }
        vis[temp] = true;
        for(int j = 1; j <= N; j ++)
            if(!vis[j])
                dis[j] = min(dis[j], mp[temp][j]);
    }

    for(int i = 1; i <= N; i ++)
        res += dis[i];

    return res;
}

int main() {
    scanf("%d", &N);
    memset(mp, inf, sizeof(mp));
    for(int i = 1; i <= N; i ++) {
        for(int j = 1; j <= N; j ++) {
            int s;
            scanf("%d", &s);
            if(s < mp[i][j]) {
                mp[i][j] = s;
                mp[j][i] = mp[i][j];
            }
        }
    }

    int sum = 0;
    scanf("%d", &P);
    for(int i = 1; i <= P; i ++) {
        int a, b;
        scanf("%d%d", &a, &b);
        mp[a][b] = mp[b][a] = 0;
    }

    int ans = prim();
    printf("%d\n", ans);
    return 0;
}