问题描述
https://leetcode.com/problems/spiral-matrix-ii/
解决思路
这题和54基本差不多，思路一样的，需要单独处理一下中间会剩下一个的情况。
代码
class Solution {
public int[][] generateMatrix(int n) {
int[][] res = new int[n][n];
if(n <= 0 ) return res;
int left = 0, right = n - 1;
int top = 0, bottom = n - 1;
int num = 1;
while(left < right && top < bottom){
for(int i = left; i < right; i++) res[top][i] = num++;
for(int i = top; i < bottom; i++) res[i][right] = num++;
for(int i = right; i > left; i--) res[bottom][i] = num++;
for(int i = bottom; i > top; i--) res[i][left] = num++;
left++;
top++;
right--;
bottom--;
}
//one blank left in the center of the matrix
if(n % 2 == 1){
res[n / 2][n / 2] = num++;
}
return res;
}
}
复杂度分析
- 时间复杂度：O(n)
- 空间复杂度：O(n^2)
