leetcode 054 Spiral Matrix

最新推荐文章于 2021-03-27 01:41:13 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给定矩阵的所有元素。通过定义边界并逐步缩小处理范围的方式实现了螺旋遍历的过程。

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].

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class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        int len = matrix.size();
		vector<int> ret;

		if(len == 0) return ret;

		int rows = len, cols = matrix[0].size();

		int beginRow=0, endRow=rows-1, beginCol=0, endCol=cols-1;
        
		for(; beginRow <= endRow && beginCol <= endCol; beginRow++, endRow--, beginCol++, endCol--) {

			int tmpCol = beginCol;
            
			while(tmpCol <= endCol) {
				ret.push_back(matrix[beginRow][tmpCol]);
				tmpCol++;
			}
            
			int tmpRow = beginRow+1;
            
			while(tmpRow <= endRow) {
				ret.push_back(matrix[tmpRow][endCol]);
				tmpRow++;
			}

			tmpCol = endCol-1;

			while(tmpCol >= beginCol && endRow > beginRow) {
				ret.push_back(matrix[endRow][tmpCol]);
				tmpCol--;
			}

			tmpRow=endRow-1;

			while(tmpRow > beginRow && endCol > beginCol) {
				ret.push_back(matrix[tmpRow][beginCol]);
				tmpRow--;
			}
			
			
		}

		return ret;
    }
};