标签：new exp img etc ati result find color ret
Given a matrix of M x N elements (M rows, N columns), return all elements of the matrix in diagonal order as shown in the below image.
Example:
Input: [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ] Output: [1,2,4,7,5,3,6,8,9] Explanation:
Walk patterns:
bottom border (row >= m) then row = m - 1; col += 2; change walk direction.right border (col >= n) then col = n - 1; row += 2; change walk direction.top border (row < 0) then row = 0; change walk direction.left border (col < 0) then col = 0; change walk direction.
Time complexity: O(m * n), m = number of rows, n = number of columns.
Space complexity: O(1).
1 public class Solution { 2 public int[] findDiagonalOrder(int[][] matrix) { 3 if (matrix == null || matrix.length == 0) return new int[0]; 4 int m = matrix.length, n = matrix[0].length; 5 6 int[] result = new int[m * n]; 7 int row = 0, col = 0, d = 0; 8 int[][] dirs = {{-1, 1}, {1, -1}}; 9 10 for (int i = 0; i < m * n; i++) { 11 result[i] = matrix[row][col]; 12 row += dirs[d][0]; 13 col += dirs[d][1]; 14 15 if (row >= m) { row = m - 1; col += 2; d = 1 - d;} 16 if (col >= n) { col = n - 1; row += 2; d = 1 - d;} 17 if (row < 0) { row = 0; d = 1 - d;} 18 if (col < 0) { col = 0; d = 1 - d;} 19 } 20 21 return result; 22 } 23 }
标签：new exp img etc ati result find color ret
原文地址：https://www.cnblogs.com/beiyeqingteng/p/12267547.html
