CodeForces-Learning Languages

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/*
这道题目考查并查集，特别注意每个人都不会语言的情况，此时结果为n。
*/
int father[105];
int lang[105][105];
int flag[105];
int set[105];


int find(int x){
    int r = x;
    while(father[r]!=r)
        r=father[r];
    //压缩
    int i = x,j;
    while(father[i]!=r){
        j=father[i];
        father[i]=r;
        i=j;
    }
    return r;
}

void merge(int x,int y){
    int fx = find(x);
    int fy = find(y);
    if (fx!=fy)
        father[fx]=fy;
}



int main(){
    freopen("0input.txt","r",stdin);
    int n,m,k,p,res,flag1=0;
    while(scanf("%d%d",&n,&m)!=EOF){
        //初始化
        flag1=0;
        memset(flag,0,sizeof(flag));
        memset(lang,0,sizeof(lang));
        memset(set,0,sizeof(set));
        for (int i = 1; i <= n; ++i)
            father[i]=i;
        //读入数据
        for (int i = 1; i <= n; ++i) 
        {
            scanf("%d",&k);
            if (k!=0)
            {
                flag[i]=1;
                for (int j = 1; j <= k; ++j)
                {
                    scanf("%d",&p);
                    lang[p][i]=1;
                }
            }
        }

        //构造并查集
        for (int i = 1; i <=m; ++i)
        {   
            int j,fa,fb;
            for (j = 1; j <= n; ++j)
            {
                if (lang[i][j]){

                    fa = find(j);
                    //printf("fa:%d\n",fa );
                    break;
                }
            }
            for (j=j+1; j <= n; ++j)
            {
                if (lang[i][j])
                {
                    fb=find(j);
                    //printf("fa:%dfb:%d\n",fa,fb);
                    merge(fa,fb);
                }
            }
        }
        for (int i = 1; i <= n; ++i)
        {
            //printf("flag:%d ",flag[i]);
            if (flag[i]){
                flag1=1;
                break;
            }
        }

        if (!flag1)
        {
            printf("%d\n",n);
        }else{

            //统计将员工分成几类
            int fc;
            for (int i = 1; i <=n; ++i)
            {
                fc = find(i);
                set[fc]++;
            }
            res =0;
            for (int i = 1; i <= n; ++i)
            {
                if (set[i]>=1)      
                    res++;
            }
            printf("%d\n",res-1);
        }


    }
    return 0;
}