The Fellow Programmer

Given a positive integer   n , generate an   n x n   matrix   filled with elements from   1   to   n 2   in spiral order. Example 1: Input: n = 3 Output: [[1,2,3],[8,9,4],[7,6,5]] Example 2: Input: n = 1 Output: [[1]]   Constraints: 1 <= n <= 20 Solution: class Solution {     public int[][] generateMatrix(int n) {         int[][] matrix = new int[n][n];         int top = 0, bottom = n - 1, left = 0, right = n - 1;         int val = 1;         while (val <= n * n) {             for (int i = left; i <= right; i++)                  matrix[top][i] = val++;              top++;             for (int i = top; i <= bottom; i++)                 matrix[i][right] = val++;             right--;             for (int i = right; i >= left; i--)                 matrix[bottom][i] = val++;              botto

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     public class Solution { public int maximalSquare(char[][] matrix) { int rows = matrix.length, cols = rows > 0 ? matrix[0].length : 0; int maxlen = 0; for (int i = 0; i < rows; i++) { for (int j = 0; j < cols; j++) { if (matrix[i][j] == '1') { int len = 1; boolean flag = true; while (len + i < rows && len + j < cols && flag) { for (int k = j; k <= len + j; k++) { if (matrix[i + len][k] == '0') { flag = false; break; } }

A binary matrix means that all elements are  0  or  1 . For each  individual row of the matrix, this row is sorted in non-decreasing order. Given a row-sorted binary matrix binaryMatrix, return leftmost column index(0-indexed) with at least a  1  in it. If such index doesn't exist, return -1 . You can't access the Binary Matrix directly.   You may only access the matrix using a  BinaryMatrix  interface: BinaryMatrix.get(x, y) returns the element of the matrix at index (x, y)  (0-indexed). BinaryMatrix.dimensions()  returns a list of 2 elements  [n, m] , which means the matrix is n * m . Submissions making more than 1000  calls to  BinaryMatrix.get  will be judged Wrong Answer .  Also, any solutions that attempt to circumvent the judge will result in disqualification. For custom testing purposes you're given the binary matrix mat  as input in the following four examples. You will not have access the binary matrix directly. It is one of FACEBOOK INTERVIEW ques