Spiral Matrix
Total Accepted: 12721 Total Submissions: 62094My Submissions
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].
题意：以螺旋顺序输入矩阵中的数值
思路：
从左到右，从上到下，从右到左，从下到上按顺序遍历
将矩阵的(0,0)元素看成坐标原点，向右为x轴正方向，向下为y轴正方向
用四个变量，即两个坐标(startx, starty), (endx, endy) 表示每轮遍历的矩阵的左上角和右下角的坐标
复杂度：时间O(n^2)
vector
spiralOrder(vector
> &matrix){ vector
res; if(matrix.empty()) return res; int startx = 0, endx = matrix[0].size() - 1; int starty = 0, endy = matrix.size() - 1; while(startx <= endx && starty <= endy){ for(int j = startx; j <= endx; ++j) res.push_back(matrix[starty][j]); starty++; for(int i = starty; i <= endy; ++i) res.push_back(matrix[i][endx ]); endx--; if(starty <= endy){ for(int j = endx; j >= startx ; --j) res.push_back(matrix[endy ][j]); endy--; } if(startx <= endx){ for(int i = endy; i >= starty; --i) res.push_back(matrix[i][startx]); startx++; } } return res; }