简单前缀和

#include<iostream>
#include<cstdlib>
using namespace std;
typedef long long ll;
ll m,n,a[100000],b[100000];
ll x,y;
int main()
{
    cin>>n;
    b[0] = 0;
    for(ll i =1;i<=n;++i)
    {
        cin>>a[i];
        b[i] = b[i-1]+a[i];
        
    }
    // for(int i =1;i<=n;++i)
    //     cout<<b[i]<<" ";
    cout<<endl;
    cin>>m;
    while(m--)
    {
        cin>>x>>y;
        printf("%lld\n",b[x+y-1]-b[x-1]);
    }
    system("pause");
    return 0;
}

#include<iostream>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;
typedef long long ll;
int t;
int mp[1005][1004];
int b[1005][1005];
int n,m,x,y;
int main()
{
    cin>>t;
    while(t--)
    {
        memset(b,0,sizeof(b));
        cin>>m>>n>>x>>y;
        for(int i =1;i<=m;++i)
        {
            for(int j =1;j<=n;++j)
            {
                cin>>mp[i][j];
                b[i][j] = b[i-1][j]+b[i][j-1]-b[i-1][j-1]+mp[i][j];
            }
        }
        int ans=0;
        for(int i =x;i<=m;++i)
        {
            for(int j =y;j<=n;++j)
            {
                ans=max(ans,b[i][j]-b[i-x][j]-b[i][j-y]+b[i-x][j-y]);
            }
        }
       cout<<ans<<endl;

    }
    system("pause");
    return 0;
}