Aizu - DPL_3_A Largest Square 【基础DP 自己还是太菜】

Given a matrix (H × W) which contains only 1 and 0, find the area of the largest square matrix which only contains 0s.

Input

H W
c

_1,1

 c

_1,2

 ... c1,W
c

_2,1

 c

_2,2

 ... c2,W
:
cH,1 cH,2 ... cH,W

In the first line, two integers H and W separated by a space character are given. In the following H lines, c_i,j, elements of the H × W matrix, are given.

Output

Print the area (the number of 0s) of the largest square.

Constraints

• 1 ≤ H, W ≤ 1,400

Sample Input

4 5
0 0 1 0 0
1 0 0 0 0
0 0 0 1 0
0 0 0 1 0

Sample Output

4

1表示有污渍
0表示干净
问最大的干净的正方形边长
f[i][j] = min(f[i-1][j],min(f[i][j-1],f[i-1][j-1]))+1;
完全没有考虑到状态之间还有这种关系，自己的思考能力才是最应该提升的。

题解

#include<iostream>
using namespace std;
#include<cstring>
#include<cstdio>
int f[1500][1500];
int a[1500][1500];
int main(){
    int n,m;
    scanf("%d%d",&n,&m);
    int maxn = 0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            scanf("%d",&a[i][j]);
            if(a[i][j]==1)
                f[i][j]=0;
            else
            f[i][j] = min(f[i-1][j],min(f[i][j-1],f[i-1][j-1]))+1;
            maxn = max(f[i][j],maxn);
        }
    }
    printf("%d\n",maxn*maxn);
    return 0;
}