题目描述

输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字。

https://leetcode.cn/problems/shun-shi-zhen-da-yin-ju-zhen-lcof/

题解

模拟

上下左右指针作为边界，遍历打印。

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        if (matrix.size() == 0 || matrix[0].size() == 0) return {};
        int left = 0, right = matrix[0].size() - 1, top = 0, bottom = matrix.size() - 1;
        vector<int> res;
        while (true) {
            // left to right
            for (int i = left; i <= right; ++i)
                res.push_back(matrix[top][i]);
            if (++top > bottom) break;
            // top to bottom
            for (int i = top; i <= bottom; ++i)
                res.push_back(matrix[i][right]);
            if (--right < left) break;
            // right to left
            for (int i = right; i >= left; --i)
                res.push_back(matrix[bottom][i]);
            if (--bottom < top) break;
            // bottom to top
            for (int i = bottom; i >= top; --i)
                res.push_back(matrix[i][left]);
            if (++left > right) break;
        }
        return res;
    }
};