題目鏈接

https://leetcode.com/problems/maximal-rectangle/

題目原文

Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.

題目大意

給出一個包含0和1的矩陣，在矩陣中找到一個矩形，這個矩形只包含1

解題思路

道題需要利用上一道題（Largest Rectangle in Histogram）的結論。比如對于以下矩陣。
0 0 0 0
0 0 1 0
0 1 1 0
1 0 1 1
對于這個矩陣，對于每一行，我們按照上一道題的算法求解一遍，最后得出的就是最大的矩陣。

代碼

class Solution(object):def largestRectangleArea(self, heights):""":type heights: List[int]:rtype: int"""stack = []i = 0area = 0while i < len(heights):if stack == [] or heights[i] > heights[stack[len(stack) - 1]]:stack.append(i)else:cur = stack.pop()if stack == []:width = ielse:width = i - stack[len(stack) - 1] - 1area = max(area, width * heights[cur])i -= 1i += 1while stack != []:cur = stack.pop()if stack == []:width = ielse:width = len(heights) - stack[len(stack) - 1] - 1area = max(area, width * heights[cur])return areadef maximalRectangle(self, matrix):""":type matrix: List[List[str]]:rtype: int"""if matrix == []:return 0a = [0 for i in range(len(matrix[0]))]maxArea = 0for i in range(len(matrix)):for j in range(len(matrix[i])):if matrix[i][j] == '1':a[j] = a[j] + 1else:a[j] = 0maxArea = max(maxArea, self.largestRectangleArea(a))return maxArea

轉載于:https://www.cnblogs.com/slurm/p/5179572.html

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