HDU 5701 中位数计数 暴力

Posted 2020-07-11 shuguangzw

老题了，附上黄学长链接一发，直接改改就AC了，http://hzwer.com/1216.html

#include <cstdio>
#include <iostream>
#include <cstring>
using namespace std;
const int N=1e4+5;
int num[N],sum[N],l[N*2],r[N*2],a[N];
int n;
int get(int x){
    int p,ans=0;
    memset(sum,0,sizeof(sum));
    memset(l,0,sizeof(l));
    memset(r,0,sizeof(r));
    for(int i=1;i<=n;i++)
    {
        if(a[i]>x)num[i]=1;
        else if(a[i]==x){num[i]=0;p=i;}
        else num[i]=-1;
    }
    l[n]=1;r[n]=1;
    for(int i=p-1;i>=1;i--)
       {sum[i]=sum[i+1]+num[i];l[sum[i]+n]++;}
    for(int i=p+1;i<=n;i++)
       {sum[i]=sum[i-1]+num[i];r[sum[i]+n]++;}
    for(int i=0;i<=2*n-1;i++)ans+=l[i]*r[2*n-i];
    return ans;
}
int main()
{
    while(~scanf("%d",&n)){
      for(int i=1;i<=n;++i)
       scanf("%d",&a[i]);
      for(int i=1;i<n;++i){
        printf("%d ",get(a[i]));
      }
      printf("%d\\n",get(a[n]));
    }
    return 0;
}

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