HDU 1232 畅通工程 并查集水题

题意

并查集算法最后得到的集合的个数减一就是结果

传送门

http://acm.hdu.edu.cn/showproblem.php?pid=1232

#include 
#include 
#include 

using namespace std;

class UnionFind {
private:
    int * fa;
    int size;
public: 
    UnionFind(int n) {
        size = n;
        fa = new int[n+1];
        Init();
    }

    ~UnionFind() {
        delete[] fa;
    }

    void Init() {
        for(int i = 1 ; i <= size ; i ++) {
            fa[i] = i;
        }
    }

    int Find(int x) {
        if(fa[x] != x) {
            fa[x] = Find(fa[x]);
        }
        return fa[x];
    }

    bool Union(int x,int y) {
        int fx = Find(x);
        int fy = Find(y);
        if(fx != fy) {
            fa[fx] = fy;
            return true;
        }
        else {
            return false;
        }
    }

    int GetCount() {
        int count = 0;
        for(int i = 1 ; i <= size ; i ++) {
            if(fa[i] == i) {
                count ++;
            }
        }
        return count;
    }

    int GetMaxSetNum() {
        int maxSetNum = 0;
        int * countSet = new int[size+1];
        memset(countSet,0,sizeof(int)*(size+1));
        for(int i = 1 ; i <= size ; i ++) {
            int fi = Find(i);
            countSet[fi] ++;
        }
        for(int i = 1 ; i <= size ; i ++) {
            if(countSet[i] > maxSetNum) {
                maxSetNum = countSet[i];
            }
        }
        delete[] countSet;
        return maxSetNum;
    }
};

int main() {
    int n,m;
    while(scanf("%d %d",&n,&m) == 2) {
        UnionFind uf(n);
        for(int i = 1 ; i <= m ;i ++) {
            int u,v;
            scanf("%d %d",&u,&v);
            uf.Union(u,v);
        }
        printf("%d\n",uf.GetCount()-1);
    }
}