21. Count_Square_Submatrices_with_All_Ones.java

class Solution {
    public int countSquares(int[][] matrix) {
        int m = matrix.length, n = matrix[0].length;
        int[][] dp = new int[m][n];
        int res = 0;
        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(i == 0 || j == 0){
                    dp[i][j] = matrix[i][j];
                }
                else{
                    dp[i][j] = matrix[i][j] == 1 ? Math.min(dp[i - 1][j], Math.min(dp[i - 1][j - 1], dp[i][j - 1])) + 1 : 0;
                }
                res += dp[i][j];
            }
        }
        
        return res;
    }
}