bzoj1303

题解：

首先把>b的标记为1

小于b的标记为－１

然后更具乘法原理做

代码：

#include<bits/stdc++.h>
using namespace std;
const int N=200005;
int num[N],sum[N],l[N],r[N],n,b,point,ans;
int main()
{
    scanf("%d%d",&n,&b);
    for (int i=1;i<=n;i++)
     {
        scanf("%d",&num[i]);
        if (num[i]>b)num[i]=1;
        else if (num[i]==b){num[i]=0;point=i;}
        else num[i]=-1;
     }
    l[n]=1;r[n]=1;
    for (int i=point-1;i>=1;i--){sum[i]=sum[i+1]+num[i];l[sum[i]+n]++;}
    for (int i=point+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];
    printf("%d",ans);
    return 0;
}