HDU_1233《还是畅通工程》

#include<iostream>#include<algorithm>#include<vector>#include<cstring>using namespace std;const int maxn = 1000 + 5;vector<int> G[maxn];int p[maxn];void init(int N) {    memset(p, 0, sizeof(p));    for(int i = 1; i <= N; i++)        p[i] = i;}int _find(int x) {return (p[x]==x ? x : _find(p[x]));}void _merge(int x, int y) {    if(_find(x)!=_find(y)) p[_find(y)] = _find(x);}void initG(int N) {for(int i = 1; i < N; i++) G[i].clear();}void read_tree(int M) {    int u, v;    for(int i = 0; i < M; i++) {            cin >> u >> v;            _merge(u, v);    }}int main() {    int N, M, cnt;    while((cin >> N) && N) {        cin >> M;        init(N); initG(N);        read_tree(M);        cnt = 0;        for(int i = 1; i <= N; i++) if(p[i] == i) cnt++;        cout << cnt-1 << endl;    }    return 0;}

直接使用并查集， 套用一下框架， 直接AC。