HDU 2870 （dp46）

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
using namespace std;


char map[1005][1005];
int dp[1005][1005];
int l[1005];
int r[1005];
int Max;
int n,m;

void DP()
{
    int i,j;
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;j++)
        {
            l[j]=j;
            while(l[j]>=2&&dp[i][j]<=dp[i][l[j]-1])
                l[j]=l[l[j]-1];
        }
        for(j=m;j>=1;j--)
        {
            r[j]=j;
        while(r[j]<=m-1&&dp[i][j]<=dp[i][r[j]+1])
            r[j]=r[r[j]+1];
        }
        for(j=1;j<=m;j++)
        if(Max<(r[j]-l[j]+1)*dp[i][j])
            Max=(r[j]-l[j]+1)*dp[i][j];
    }
}

int main()
{
    int i,j;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        Max=0;
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=m;j++)
            {
                cin>>map[i][j];
            }
        }
    memset(dp,0,sizeof(dp));
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;j++)
        {
            if(map[i][j]=='a'||map[i][j]=='w'||map[i][j]=='y'||map[i][j]=='z')
                dp[i][j]=dp[i-1][j]+1;
        }
    }
    DP();
    memset(dp,0,sizeof(dp));
    for(i=1;i<=n;i++)
    {
    for(j=1;j<=m;j++)
        {
            if(map[i][j]=='b'||map[i][j]=='w'||map[i][j]=='x'||map[i][j]=='z')
                dp[i][j]=dp[i-1][j]+1;
        }
    }
    DP();
    memset(dp,0,sizeof(dp));
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;j++)
        {
            if(map[i][j]=='c'||map[i][j]=='x'||map[i][j]=='y'||map[i][j]=='z')
                dp[i][j]=dp[i-1][j]+1;
        }
    }
    DP();
    printf("%d\n",Max);
    }
    return 0;
}