题目描述

给定一个包含 m x n 个元素的矩阵(m 行, n 列),请按照顺时针螺旋顺序,返回矩阵中的所有元素。

示例一

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

示例二

输入:
[
[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]

思路

逐层遍历,请参看代码

参考代码

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

谢谢访问