[每日一题]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:The total number of elements of the given matrix will not exceed 10,000.提示：提交代码后，需要用简洁的语言解释一下代码思路~ 谢谢历史题目和总结见公众号「每日一道算法题」https://leetcode.com/problems/diagonal-traverse/description/小Fu视频讲解 ………………………………