题解 | 对角线遍历矩阵

class Solution {
  public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param mat int整型vector<vector<>>
     * @return int整型vector
     */
    vector<int> diagonalOrder(vector<vector<int> >& mat) {
        // write code here
        int row = mat.size();
        int column = mat[0].size();
        int count = row * column;
        vector<int> result;
        bool isUp = true;
        int x = 0;
        int y = 0;
        while (result.size() < count) {
            result.push_back(mat[x][y]);
            if (isUp) {
                if (y == column - 1) {
                    x++;
                    isUp = false;
                    continue;
                } else if (x == 0) {
                    y++;
                    isUp = false;
                    continue;
                }
                x--;
                y++;
            } else {
                if (x == row - 1) {
                    y++;
                    isUp = true;
                    continue;
                } else if (y == 0) {
                    x++;
                    isUp = true;
                    continue;
                }

                y--;
                x++;
            }
        }

        return result;
    }
};

单纯的循环，注意边界条件