LeetCode 面试经典150题 [34/150 螺旋矩阵]

题目描述

给你一个 m 行 n 列的矩阵 matrix ，请按照 顺时针螺旋顺序 ，返回矩阵中的所有元素。
示例 1：

输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出：[1,2,3,6,9,8,7,4,5]

示例 2：

输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
输出：[1,2,3,4,8,12,11,10,9,5,6,7]

个人C++解答

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        int up = 0, down = matrix.size() - 1, left = 0,
            right = matrix[0].size() - 1;
        vector<int> result;
        while (left <= right && up <= down) {
            for (int i = left; i <= right; i++)
                result.push_back(matrix[up][i]);
            up++;
            for (int i = up; i <= down; i++)
                result.push_back(matrix[i][right]);
            right--;
            if (up <= down)
                for (int i = right; i >= left; i--)
                    result.push_back(matrix[down][i]);
            down--;
            if (left <= right)
                for (int i = down; i >= up; i--)
                    result.push_back(matrix[i][left]);
            left++;
        }
        return result;
    }
};