1002. 二哥种花生

容斥原理的简单应用

#include <bits/stdc++.h>using namespace std;#define maxn 1005int d[maxn][maxn];int main(){int l,w;cin>>l>>w;memset(d,0,sizeof(d));for (int i=1;i<=l;i++){for (int j=1;j<=w;j++){cin>>d[i][j];d[i][j]=d[i][j]+d[i-1][j]+d[i][j-1]-d[i-1][j-1];}}int a,b;cin>>a>>b;int ans=0;for (int i=a;i<=l;i++){for (int j=b;j<=w;j++){ans=max(ans,  d[i][j]-d[i-a][j]-d[i][j-b]+d[i-a][j-b] );}}cout<<ans<<endl;return 0;}