luogu1169 [ZJOI2007]棋盘制作

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int n, m, h[2005][2005], l[2005][2005], r[2005][2005], uu, iii=0, jjj=0;
bool a[2005][2005];
void rn(int &x){
    char ch=getchar();
    x = 0;
    while(ch<‘0‘ || ch>‘9‘) ch = getchar();
    while(ch>=‘0‘ && ch<=‘9‘){
        x = x * 10 + ch - ‘0‘;
        ch = getchar();
    }
}
void work(){
    int ans=0, maxn=0;
    memset(h, 0, sizeof(h));
    for(int i=1; i<=n; i++){
        int x=1;
        for(int j=1; j<=m; j++)
            if(a[i][j]) l[i][j] = x;
            else    l[i][j] = 1, x = j + 1;
        x = m;
        for(int j=m; j>=1; j--)
            if(a[i][j]) r[i][j] = x;
            else    r[i][j] = m, x = j - 1;
    }
    for(int i=1; i<=m; i++) l[0][i] = 1, r[0][i] = m;
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
            if(a[i][j]){
                h[i][j] = h[i-1][j] + 1;
                l[i][j] = max(l[i][j], l[i-1][j]);
                r[i][j] = min(r[i][j], r[i-1][j]);
                ans = max(ans, (r[i][j]-l[i][j]+1)*h[i][j]);
                maxn = max(maxn, min(h[i][j], (r[i][j]-l[i][j]+1)));
            }
    iii = max(iii, maxn*maxn);
    jjj = max(jjj, ans);
}
int main(){
    cin>>n>>m;
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++){
            rn(uu);
            a[i][j] = uu;
            if((i+j)%2==0)  a[i][j] ^= 1;
        }
    work();
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
            a[i][j] ^= 1;
    work();
    cout<<iii<<endl<<jjj<<endl;
    return 0;
}