HDU 2870 DP 最大完全子矩阵

HDU 1505 升级版

枚举a，b，c  各做一遍最大完全子矩阵

#include "stdio.h"
#include "string.h"

char a[1010][1010];
int n,m,ans;
int sum[1010][1010];

int max(int a,int b)
{
    if (a<b) return b;
    else return a;
}
void solve(char key)
{
    int i,j;
    int le[1010],ri[1010];

    memset(sum,0,sizeof(sum));
    for (i=0; i<n; i++)
        for (j=0; j<m; j++)
        {
            if (key=='a' && (a[i][j]=='w' || a[i][j]=='y' || a[i][j]=='z' || a[i][j]=='a'))  sum[i][j]=sum[i][j-1]+1;
            if (key=='b' && (a[i][j]=='w' || a[i][j]=='x' || a[i][j]=='z' || a[i][j]=='b'))  sum[i][j]=sum[i][j-1]+1;
            if (key=='c' && (a[i][j]=='x' || a[i][j]=='y' || a[i][j]=='z' || a[i][j]=='c'))  sum[i][j]=sum[i][j-1]+1;
        }

    for (j=0; j<m; j++)
    {
        for (i=0; i<n; i++)
            le[i]=ri[i]=i;

        for (i=0; i<n; i++)
            while (sum[i][j]<=sum[le[i]-1][j] && le[i]>0)
                le[i]=le[le[i]-1];

        for (i=n-1; i>=0; i--)
            while (sum[i][j]<=sum[ri[i]+1][j] && ri[i]<n-1)
                ri[i]=ri[ri[i]+1];

        for (i=0; i<n; i++)
            ans=max(ans,(ri[i]-le[i]+1)*sum[i][j]);

    }



}
int main()
{
    int i;
    while (scanf("%d%d",&n,&m)!=EOF)
    {
        getchar();
        for (i=0; i<n; i++)
            gets(a[i]);

        ans=0;
        solve('a');
        solve('b');
        solve('c');
        printf("%d\n",ans);
    }
}