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
            area[i][0] = matrix[i][0]=='1'? 1:0;
            max = Math.max(area[i][0],max);
        }
        for(int j=0;j
            area[0][j] = matrix[0][j]=='1'? 1:0;
            max = Math.max(area[0][j],max);
 
        }
        for(int i=1;i
            for(int j=1;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;
    }
}