class Solution(object):
def maximalSquare(self, matrix):
"""
:type matrix: List[List[str]]
:rtype: int
"""
rows, max_size = len(matrix), 0
'''
size[i]: the current number of continuous '1's in a column of matrix. Reset when discontinued.
The idea is to do a by-row scan, updating size[i]
Then check if there are continuous elements in size whose value is bigger than current maximal size.
'''
if rows > 0:
cols = len(matrix[0])
size = [0] * cols
for x in xrange(rows):
# update size
count, size = 0, map(lambda x, y: x+1 if y == '1' else 0, size, matrix[x])
for y in xrange(cols):
# find the maximum number of continuous elements bigger than max_size
if size[y] > max_size:
count += 1
#if more than current max_size value, increase max_size by one
if count > max_size:
# increase maximal size by 1
max_size += 1
break
else:
count = 0
print max_size
return max_size*max_size
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