2020-10-31 54.螺旋矩阵

54. 螺旋矩阵

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]

 左神方法的的C++写法

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& matrix) {
        vector<int> res;
        if(matrix.empty()) {
            return res;
        }
        int startRow = 0, startCol = 0;
        int endRow = matrix.size() - 1, endCol = matrix[0].size() - 1;
        while(startRow <= endRow && startCol <= endCol) {
            circleMatrix(matrix, res, startRow++, startCol++, endRow--, endCol--);
        }
        return res;
    }
 
    void circleMatrix(vector<vector<int>>& matrix, vector<int>& res, int startRow, int startCol, int endRow, int endCol) {
        if(startRow == endRow) {
            for(int i = startCol; i <= endCol; i ++) {
                res.push_back(matrix[startRow][i]);
            }
        } else if(startCol == endCol) {
            for(int i = startRow; i <= endRow; i ++) {
                res.push_back(matrix[i][startCol]);
            }
        } else {
            for(int curCol = startCol; curCol < endCol; curCol++) {
                res.push_back(matrix[startRow][curCol]);
            }
            for(int curRow = startRow; curRow < endRow; curRow++) {
                res.push_back(matrix[curRow][endCol]);
            }
            for(int curCol = endCol; curCol > startCol; curCol--) {
                res.push_back(matrix[endRow][curCol]);
            }
            for(int curRow = endRow; curRow > startRow; curRow--) {
                res.push_back(matrix[curRow][startCol]);
            }
        }
    }
};