前缀和操作

代码

#include<bits/stdc++.h>
using namespace std;
const int N = 1010;
int a[N][N];
int n,l,r,t;
int cnt;
int main()
{
    cin>>n>>l>>r>>t;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            cin>>a[i][j];
            a[i][j]=a[i-1][j]+a[i][j-1]+a[i][j]-a[i-1][j-1];
        }
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            int x1,y1,x2,y2;
            if(i+r>n)x1=n;else x1=i+r;
            if(j+r>n)y1=n;else y1=j+r;
            if(i-r<1)x2=1;else x2=i-r;
            if(j-r<1)y2=1;else y2=j-r;
            int s=a[x1][y1]-a[x1][y2-1]-a[x2-1][y1]+a[x2-1][y2-1];
            if(s<=t*(x1-x2+1)*(y1-y2+1))cnt++;
        }
    }
    cout<<cnt;
    return 0;
}