poj1611

简单并查集

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#include <iostream>

#include <cstdlib>

#include <cstdio>

#include <cstring>

using namespace std;



#define maxn 30005



int n, m;

int father[maxn];

int stk[maxn];



void init()

{

    for (int i = 0; i < n; i++)

        father[i] = i;

}



int getanc(int a)

{

    int top = 0;

    while (father[a] != a)

    {

        stk[top++] = a;

        a = father[a];

    }    

    while (top)

        father[stk[--top]] = a;

    return a;

}



void merge(int a, int b)

{

    int x = getanc(a);

    int y = getanc(b);

    father[x] = father[y];

}



void input()

{

    int k;

    for (int i = 0; i < m; i++)

    {

        scanf("%d", &k);

        if (k == 0)

            continue;

        int a, b;

        scanf("%d", &a);

        for (int j = 1; j < k; j++)

        {

            scanf("%d", &b);

            merge(a, b);

        }

    }

}



int work()

{

    int ret = 0;

    for (int i = 0; i < n; i++)

        if (getanc(i) == getanc(0))

            ret++;

    return ret;

}



int main()

{

    //freopen("t.txt", "r", stdin);

    while (scanf("%d%d", &n, &m), n | m)

    {

        init();

        input();

        printf("%d\n", work());

    }

    return 0;

}