【HDU1232】畅通工程（并查集基础题）

裸敲并查集，很水一次AC

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cctype>
#include <cmath>
#include <algorithm>
#include <numeric>
#include <string>

#pragma comment(linker, "/STACK:102400000,102400000")
using namespace std;

int cnt = 0;
const int V = 1005;
int father[V];

int getFather (int x) {
    if (father[x] != x) {
        father[x] = getFather (father[x]);
    }
    return father[x];
}

void Union (int p, int q) {
    int x = getFather (p);
    int y = getFather (q);
    if (x != y) {
        father[y] = x;
        cnt ++;
    }
}

int main () {
    int n, road_n;
    while (~scanf("%d", &n)) {
        if (!n) break;
        scanf("%d", &road_n);//cin >> road_n;
        cnt = 0;
        for (int i = 0; i <= n; ++ i) {
            father[i] = i;
        }

        for (int i = 0 ; i < road_n; ++ i) {
            int x, y; //cin >> x >> y;
            scanf("%d%d", &x, &y);
            Union (x, y);
        }
        //cout << "cnt :   " << cnt << endl;
        cout << n - 1 - cnt << endl;
    }
    return 0;
}