Diagonal Traverse问题及解法

问题描述：

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:

问题分析：

以横纵坐标为准线，将对应的值保存到结果集中去。

过程详见代码：

class Solution {public:    vector<int> findDiagonalOrder(vector<vector<int>>& matrix) {vector<int> res;int m = matrix.size();if (!m) return res;int n = matrix[0].size(), flag = 0;// flag = 0表示斜向上,flag = 1表示斜向下int i = 1, j = -1,num = m * n,t = 0;res.resize(num);while (t < num){if (!flag){if (isGood(i - 1, j + 1, m, n)){res[t] = (matrix[--i][++j]);}else{if (j + 1 < n){res[t] = (matrix[i][++j]);}else if (i + 1 < m){res[t] = (matrix[++i][j]);}flag = 1;}}else{if (isGood(i + 1, j - 1, m, n)){res[t] = (matrix[++i][--j]);}else{if (i + 1 < m){res[t] = (matrix[++i][j]);}else if (j + 1 < n){res[t] = (matrix[i][++j]);}flag = 0;}}t++;}return res;}bool isGood(int i, int j, int m ,int n){return i < m && i >= 0 && j < n && j >= 0;}};