# LeetCode - 498. Diagonal Traverse

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:


Note:

1. The total number of elements of the given matrix will not exceed 10,000.
class Solution {
public int[] findDiagonalOrder(int[][] matrix) {
boolean up = true;
if (matrix.length == 0) return new int[0];
int[] res = new int[matrix.length * matrix[0].length];
int i = 0;
int j = 0;
for (int k = 0; k < matrix.length * matrix[0].length; k++) {
res[k] = matrix[i][j];
if (up) {
if ((i-1) >= 0 && (j+1) < matrix[0].length) {
i--;
j++;
} else if ((j+1) < matrix[0].length) {
j++;
up = false;
} else if ((i+1) < matrix.length) {
i++;
up = false;
} else break;
} else {
if ((i+1) < matrix.length && (j-1) >= 0) {
i++;
j--;
} else if ((i+1) < matrix.length) {
i++;
up = true;
} else if ((j+1) < matrix[0].length) {
j++;
up = true;
} else break;
}
}
return res;

}
}

posted @ 2018-08-16 14:59  Pickle  阅读(314)  评论(0编辑  收藏  举报