- Chessboard Traveling

- MaximalSquare

I think this one is very hard when it comes to matrix and filter, and how to handle filter movement within a matrix by pure code without using some matrix handling library.

Since coderbyte uses python2, and my own laptop uses python3, I have 2 version of the code.

For python2 version, you can just copy and paste the code on to the [coderbyte online editor](https://www.coderbyte.com/information/Maximal%20Square) and test the code.

For python3, you can run it on your own computer. You need to copy and paste the test case on strArr, for example:

'''

strArr = ["0111", "1111", "1111", "1111"]

'''

Have fun!

def MaximalSquare(strArr):

l = list([[int(x) for x in s] for s in strArr])

row = len(strArr)

col = len(strArr[0])

F = min(row, col)

for f in range(F, 0, -1): # descending searching

for i in range(0, row-f+1): # from row to row (filter goes from upper to bottom)

# if f == row, do this for loop only once

# i is the row index of the matrix

for j in range(0, col-f+1): # from column to column (filter goes from left to right)

# if f == col, do this loop only once

# j is the column index of the matrix

# strArr[i][j] is the upper left corner of the submatrix

multiply = 1

# l[m][n] is the elements of the submatrix

for m in range(i, f+i):

for n in range(j, f+j):

multiply *= l[m][n]

## after all the multiply operator:

if multiply == 1:

return f*f

return 0

print MaximalSquare(raw_input())

def MaximalSquare(strArr):

l = list([[int(x) for x in s] for s in strArr])

#print(l)

row = len(strArr)

col = len(strArr[0])

F = min(row, col)

#print("row, col = ", row, ', ', col)

#print("original F =", F)

for f in range(F, 0, -1): # descending searching

#print("======================================================\nfilter size = ", f)

for i in range(0, row-f+1): # from row to row (filter goes from upper to bottom)

# if f == row, do this for loop only once

# i is the row index of the matrix

for j in range(0, col-f+1): # from column to column (filter goes from left to right)

# if f == col, do this loop only once

# j is the column index of the matrix

# strArr[i][j] is the upper left corner of the submatrix

#print(f'Top left coordinate of the submatrix is: i, j = {i}, {j}')

multiply = 1

# l[m][n] is the elements of the submatrix

for m in range(i, f+i):

for n in range(j, f+j):

#print(f'm, n = {m}, {n}')

multiply *= l[m][n]

#print(f'multiply = {multiply}')

## after all the multiply operator:

if multiply == 1:

return f*f

return 0

strArr = ["0111", "1111", "1111", "1111"]

print(MaximalSquare(strArr))