hdu1856

题意：就是询问下，一个并查集里面结点数最多的....并输出来，大致是这个意思吧，当然可以离散化下，水题.....

#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

using namespace std;

#define M 100005

struct

{

    int father;

    int sum;

} s[4*M];

int t[2*M][2],a[2*M];

int find(int x)

{

    int i=x,root;

    while(x!=s[x].father)

        x=s[x].father;

    root=x;

    x=i;

    while(x!=s[x].father)

    {

        i=s[x].father;

        s[root].sum+=s[x].sum;

        s[x].sum=0;

        s[x].father=root;

        x=i;

    }

    return root;

}

void liantong(int x,int y)

{

    s[x].sum+=s[y].sum;

    s[y].father=x;

    s[y].sum=0;

}

int erfen(int ll,int rr,int num)

{

    while(ll<=rr)

    {

        int mid=(ll+rr)/2;

        if(a[mid]>num)

        rr=mid-1;

        else

        ll=mid+1;

    }

    //printf("%d %d\n",a[rr],num);

    return rr;

}

int main()

{

    int n;

    while(scanf("%d",&n)>0)

    {

        int ans=0;

        int cnt=0;

        for(int i=0; i<=3*100005; i++)

        {

            s[i].father=i;

            s[i].sum=1;

        }

        //scanf("")

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

        {

            scanf("%d%d",&t[i][0],&t[i][1]);

            a[cnt++]=t[i][0];

            a[cnt++]=t[i][1];

        }

        sort(a,a+cnt);

        int cnt1=1;

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

            if(a[i]!=a[i-1])   a[cnt1++]=a[i];

        for(int i=cnt1-1; i>0; i--)

            if(a[i]!=a[i-1]+1)   a[cnt1++]=a[i-1]+1;

        sort(a,a+cnt1);

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

        {

            int left=0,right=cnt1-1;

            int x=erfen(left,right,t[i][0]);

            int y=erfen(left,right,t[i][1]);

            x=find(x);

            y=find(y);

            if(x!=y)

                liantong(x,y);

        }

        for(int i=0;i<=2*100005;i++)

        find(i);

        int ans1=0;

        for(int i=0;i<=2*100005;i++)

        if(ans1<s[i].sum)

        ans1=s[i].sum;

        printf("%d\n",ans1);

    }

    return 0;

}