题目：
给定一个仅包含 0 和 1 的二维二进制矩阵，找出只包含 1 的最大矩形，并返回其面积。
思路：
使用head和tail来构建以某点为基准的矩形的宽，使用height来定义以某点为基准的矩形的高。
程序：
class Solution:
def maximalRectangle(self, matrix: List[List[str]]) -> int:
if not matrix:
return 0
row = len(matrix)
column = len(matrix[0])
if row <= 0:
return 0
if column <= 0:
return 0
head = [-1] * column
tail = [column] * column
height = [0] * column
result = 0
for index1 in range(row):
current_head = -1
current_tail = column
for index2 in range(column):
if matrix[index1][index2] == "1":
height[index2] += 1
else:
height[index2] = 0
for index2 in range(column):
if matrix[index1][index2] == "1":
head[index2] = max(head[index2], current_head)
else:
head[index2] = -1
current_head = index2
for index2 in range(column - 1, -1, -1):
if matrix[index1][index2] == "1":
tail[index2] = min(tail[index2], current_tail)
else:
tail[index2] = column
current_tail = index2
for index2 in range(column):
result = max(result, (tail[index2] - head[index2] - 1) * height[index2])
return result