{leetcode}/problems/maximal-square/[LeetCode - Maximal Square^]
Given a 2D binary matrix filled with 0’s and 1’s, find the largest square containing only 1’s and return its area.
Example:
Input: 1 0 1 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0 1 0 Output: 4
根据左上、左边、上边加自身，确定一个最小正方形；然后再进一步，在小正方形基础上，从四周选择已有正方形中最小，然后扩大，再这个过程中记录下最大的正方形边长，即可得到结果。思路如下图：
简化一下，不需要矩阵来存储所有正方形的计算结果，只需要一行来记录上一行计算结果和当前行计算结果即可。
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{leetcode}/problems/maximal-square/solution/[Maximal Square solution - LeetCode^]
Given a 2D binary matrix filled with 0’s and 1’s, find the largest square containing only 1’s and return its area.
Example:
Input: * 1 0 1 0 0 1 0 <font color="red">1 <font color="red">1 1 1 1 <font color="red">1 <font color="red">1 1 1 0 0 1 0 *Output: 4
link:{sourcedir}/_0221_MaximalSquare.java[role=include]