HDOJ 1856 More is better

转自：wutianqi http://www.wutianqi.com/?p=1069

tag：并查集

#include <iostream>

using namespace std;

 

#define MAX 10000001

 

// father[x]表示x的父节点

int father[MAX];

// rank[x]表示x的秩

int rank[MAX];

 

// 初始化

void Make_Set(int n)

{

    for(int i=1; i<=n; ++i)

    {

        father[i] = i;

        rank[i] = 1;

    }

}

 

// 查找

int Find_Set(int x)

{

    if(x != father[x])

        return Find_Set(father[x]);

    return x;

}

 

// 合并

void Union(int x, int y)

{

    x = Find_Set(x);

    y = Find_Set(y);

    if(x == y)  // x,y在同一个集合

        return;

    if(rank[x] > rank[y])

    {

        father[y] = x;

        rank[x] += rank[y];

    }

    else if(rank[x] < rank[y])

    {

        father[x] = y;

        rank[y] += rank[x];

    }

    else

    {

        father[x] = y;

        //rank[y]++;

        rank[y] += rank[x];

    }

 

}

 

int main()

{

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

    int a, b;

    int nNum;

    while(scanf("%d", &nNum) != EOF)

    {

        Make_Set(MAX);

        if(nNum==0)

        {

            printf("1\n");

            continue;

        }

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

        {

            scanf("%d %d", &a, &b);

            Union(a, b);

            //printf("rank[%d]=%d rank[%d]=%d\n", a, rank[a], b, rank[b]);

        }

        int _max=0;

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

            //printf("%d ", rank[i]);

            if(_max < rank[i])

                _max = rank[i];

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

    }

    return 0;

}