Solution
from typing import List
class Solution:
def maximalRectangle(self, matrix: List[List[str]]) -> int:
if not matrix or not matrix[0]:
return 0
heights = [0] * len(matrix[0])
ans = 0
for row in matrix:
for j, v in enumerate(row):
if v == "1":
heights[j] += 1
else:
heights[j] = 0
ans = max(ans, self.largestRectangleArea(heights))
return ans
def largestRectangleArea(self, heights: List[int]) -> int:
n = len(heights)
stk = []
left = [-1] * n
right = [n] * n
for i, h in enumerate(heights):
while stk and heights[stk[-1]] >= h:
stk.pop()
if stk:
left[i] = stk[-1]
stk.append(i)
stk = []
for i in range(n - 1, -1, -1):
h = heights[i]
while stk and heights[stk[-1]] >= h:
stk.pop()
if stk:
right[i] = stk[-1]
stk.append(i)
return max(h * (right[i] - left[i] - 1) for i, h in enumerate(heights))
if __name__ == "__main__":
sol = Solution()
mat = [
["1","0","1","0","0"],
["1","0","1","1","1"],
["1","1","1","1","1"],
["1","0","0","1","0"]
]
print(sol.maximalRectangle(mat)) # 6