LeetCode 54.Spiral Matrix (螺旋矩阵)

ゝ一世哀愁。 2022-05-10 03:46 177阅读 0赞

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 1:**

输入:
    [
     [ 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:
    [
      [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]

AC C++ Solution:

class Solution {
    public:
        vector<int> spiralOrder(vector<vector<int>>& matrix) {
            vector<int> res;
            
            if(matrix.size() == 0) {
                return res;
            }
            
            int rowBegin = 0;
            int rowEnd = matrix.size()-1;
            int colBegin =  0;
            int colEnd = matrix[0].size()-1;
            
            while(rowBegin <= rowEnd && colBegin <= colEnd) {
                //向右遍历
                for (int i = colBegin; i <= colEnd; i++)
                    res.push_back(matrix[rowBegin][i]);
                rowBegin++;
                
                //向下遍历
                for (int i = rowBegin; i <= rowEnd; i++)
                    res.push_back(matrix[i][colEnd]);
                colEnd--;
                
                //向左遍历
                if(rowBegin <= rowEnd) {
                    for(int i = colEnd; i >= colBegin; i--)
                        res.push_back(matrix[rowEnd][i]);
                }
                rowEnd--;
                
                //向上遍历
                if(colBegin <= colEnd) {
                    for(int i = rowEnd; i >= rowBegin; i--)
                        res.push_back(matrix[i][colBegin]);
                }
                colBegin++;
            }
            
            return res;
        }
    };