BZOJ 1057: [ZJOI2007]棋盘制作

/**************************************************************
    Problem: 1057
    User: BeiYu
    Language: C++
    Result: Accepted
    Time:1384 ms
    Memory:95508 kb
****************************************************************/
 
#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
 
#define sqr(x) ((x)*(x))
const int N = 2005;
 
int n,m,ans1,ans2;
int a[N][N],f[N][N],pre[N][N],nxt[N][N],L[N][N],R[N][N];
 
inline int in(int x=0,char ch=getchar()){ while(ch>‘9‘ || ch<‘0‘) ch=getchar();
    while(ch>=‘0‘ && ch<=‘9‘) x=(x<<3)+(x<<1)+ch-‘0‘,ch=getchar();return x; }
void work(){
    memset(nxt,0,sizeof(nxt)),memset(pre,0,sizeof(pre));
    for(int i=1;i<=n;i++){
        pre[i][1]=1,nxt[i][m]=m;
        for(int j=2;j<=m;j++){
            if(a[i][j]^a[i][j-1]) pre[i][j]=pre[i][j-1];
            else pre[i][j]=j;
        }for(int j=m-1;j;--j){
            if(a[i][j]^a[i][j+1]) nxt[i][j]=nxt[i][j+1];
            else nxt[i][j]=j;
        }
    }
    for(int j=1;j<=m;j++) f[1][j]=1,L[1][j]=pre[1][j],R[1][j]=nxt[1][j],ans1=max(ans1,(R[1][j]-L[1][j]+2)),ans2=max(ans2,1);
    for(int i=2;i<=n;i++) for(int j=1;j<=m;j++){
        if(a[i][j]^a[i-1][j]){
            f[i][j]=f[i-1][j]+1;
            L[i][j]=max(pre[i][j],L[i-1][j]);
            R[i][j]=min(nxt[i][j],R[i-1][j]);
        }else{
            f[i][j]=1;
            L[i][j]=pre[i][j];
            R[i][j]=nxt[i][j];
        }
        ans1=max(ans1,f[i][j]*(R[i][j]-L[i][j]+1));
        ans2=max(ans2,sqr(min(f[i][j],R[i][j]-L[i][j]+1)));
    }
//  for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) printf("%d%c",pre[i][j]," \n"[j==m]);
//  for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) printf("%d%c",nxt[i][j]," \n"[j==m]);
}
int main(){
    n=in(),m=in();
    for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) a[i][j]=in();
    work();
    cout<<ans2<<endl<<ans1<<endl;
    return 0;
}