#P3494. Largest Submatrix of All 1’s

    ID: 2504 远端评测题 5000ms 128MiB 尝试: 0 已通过: 0 难度: (无) 上传者: 标签>POJ Founder Monthly Contest – 2008.01.31, xfxyjwf

Largest Submatrix of All 1’s

Description

Given a m-by-n (0,1)-matrix, of all its submatrices of all 1’s which is the largest? By largest we mean that the submatrix has the most elements.

Input

The input contains multiple test cases. Each test case begins with m and n (1 ≤ m, n ≤ 2000) on line. Then come the elements of a (0,1)-matrix in row-major order on m lines each with n numbers. The input ends once EOF is met.

Output

For each test case, output one line containing the number of elements of the largest submatrix of all 1’s. If the given matrix is of all 0’s, output 0.

样例输入 1

2 2
0 0
0 0
4 4
0 0 0 0
0 1 1 0
0 1 1 0
0 0 0 0

样例输出 1

0
4

Source

POJ Founder Monthly Contest – 2008.01.31, xfxyjwf