Spiral Matrix [leetcode]

最新推荐文章于 2021-05-06 16:48:45 发布

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本文介绍了一种矩阵螺旋遍历的算法实现，该算法能够按螺旋顺序返回矩阵的所有元素。以一个m x n的矩阵为例，给出了具体的实现代码，并通过一个示例说明了如何使用该算法。

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

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

You should return [1,2,3,6,9,8,7,4,5].

vector<int> spiralOrder(vector<vector<int> > &matrix) {
        int layer = 0;
        vector<int> res;
        int m = matrix.size();
        if (m == 0) return res;
        int n = matrix[0].size();
        if (n == 0) return res;
        while (true)
        {
            if (layer >= n - layer) break;
            for (int i = layer; i < n - layer; i++) res.push_back(matrix[layer][i]);
            if (layer + 1 >= m - layer) break;
            for (int i = layer + 1; i < m - layer; i++) res.push_back(matrix[i][n-layer-1]);
            if (n - layer - 2 < layer) break;
            for (int i = n - layer - 2; i >= layer; i-- ) res.push_back(matrix[m-layer-1][i]);
            if (m - layer - 2 < layer + 1) break;
            for (int i = m - layer - 2; i >= layer + 1; i--) res.push_back(matrix[i][layer]);
            layer++;
        }
        return res;
    }