20200915

如果是正方形，字首和即可

現在是菱形，就將座標變換 (x,y)->(x+y,x-y)

可以發現菱形變成了正方形，字首和

#include<bits/stdc++.h>
#define ll long long
const ll INF=6e18;
using namespace std;

    long long Seed,a,b,c,MOD;
    long long Random() {
        c++;
        Seed=(Seed*a+b*c)%MOD;
        return Seed;
    }
    int Random_int() {
        
 
int tmp=Random();
        if(Random()&1)tmp*=-1;
        return tmp;
    }
    
const int N=6005,M=3005;
int A[M][M],B[N][N],n,m,h;
ll s[N][N];

    void MAKE(){
        scanf("%lld%lld%lld%lld%lld",&Seed,&a,&b,&c,&MOD);
        for(int i=1;i<=n;i++)
            for(int j=1;j<=m;j++)
                A[i][j]
 
=Random_int();
    }

int main() {
    freopen("rhombus.in","r",stdin);
    freopen("rhombus.out","w",stdout);
    int ty; scanf("%d%d%d%d",&n,&m,&h,&ty);
    if(!ty) {
        for(int i=1;i<=n;i++) 
            for(int j=1;j<=m;j++) scanf("%d",&A[i][j]);
    } else MAKE();
    
 
for(int i=1;i<=n;i++) {
        for(int j=1;j<=m;j++) {
            B[i+j][i-j+m]=A[i][j];
        }
    }
    for(int i=1;i<=n+m;i++) {
        for(int j=1;j<=n+m;j++) {
            s[i][j]=s[i-1][j]+s[i][j-1]-s[i-1][j-1]+B[i][j];
        }
    }
    ll ans=-INF;
    for(int i=1;i<=n;i++) {
        if(i-h+1<=0||i+h-1>n) continue; 
        for(int j=1;j<=m;j++) {
            if(j-h+1<=0||j+h-1>m) continue;
            int X2=i+j+h-1,X1=i+j-h+1,Y2=i-j+h-1+m,Y1=i-j-h+1+m;
            ans=max(ans,s[X2][Y2]-s[X2][Y1-1]-s[X1-1][Y2]+s[X1-1][Y1-1]);
        }
    }
    printf("%lld\n",ans);
    return 0;
}

最大菱形和