poj 2443 分类： poj 2015-04-13 19:35 36人阅读 评论(0) 收藏

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判断两个元素是否在同一集合。

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solution: 每个元素开hash记录该元素在那些集合内，压位+位运算优化即可~

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#include<cstdio>
#include<cstdlib>
#include<algorithm>

const int MAXN = 1005, MAXM = 1e4+5;

int n, s, Q;
int ins[MAXM][40] = {0};

int main()
{
#ifndef ONLINE_JUDGE
    freopen("poj2443.in","r",stdin);
    freopen("poj2443.out","w",stdout);
#endif

    scanf("%d",&n); s = n/30 + (int)(n%30!=0);

    for(int i = 1, ci; i <= n; i++)
    {
       scanf("%d",&ci);
       int s1 = i/30, s2 = i%30;
       for(int j = 1, p; j <= ci; j++)
         {scanf("%d",&p); ins[p][s1] |= 1 << s2;}
    }
    scanf("%d",&Q);
    while(Q--)
    {
       int x,y;
       bool flag = false;

       scanf("%d%d",&x,&y);
       for(int i = 0; i <= s; i++)
         if(ins[x][i]&ins[y][i])
         {flag = true; break;}

       puts(flag?"Yes":"No");
    }

#ifndef ONLINE_JUDGE
    fclose(stdin);
    fclose(stdout);
#endif
    return 0;
}

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