动态规划12（Leetcode221最大正方形）

代码：

class Solution {public int maximalSquare(char[][] matrix) {int m = matrix.length;int n = matrix[0].length;int[][]area = new int[m][n];area[0][0] = matrix[0][0];int max = 0;for(int i=0;i<m;i++){area[i][0] = matrix[i][0]=='1'? 1:0;max = Math.max(area[i][0],max);}for(int j=0;j<n;j++){area[0][j] = matrix[0][j]=='1'? 1:0;max = Math.max(area[0][j],max);}for(int i=1;i<m;i++){for(int j=1;j<n;j++){if(matrix[i][j]=='0'){area[i][j] = 0;}else if(area[i-1][j-1]==area[i][j-1]&&area[i-1][j-1]==area[i-1][j]){area[i][j] = area[i-1][j-1]+1;max = Math.max(area[i][j],max);}else{area[i][j] = Math.min(Math.min(area[i-1][j-1],area[i-1][j]),area[i][j-1])+1;}              }}return max*max;}
}