题目描述:
给定一个正整数 n, 生成一个包含 1 到 n2 所有元素, 且元素按顺时针顺序螺旋排列的正方形矩阵.
示例:
输入: 3
输出:
- [
- [ 1, 2, 3 ],
- [ 8, 9, 4 ],
- [ 7, 6, 5 ]
- ]
思想:
上 -> 右 -> 下 -> 左 循环赋值
代码:
- class Solution {
- public:
- vector<vector<int>> generateMatrix(int n) {
- vector<vector<int>> ans(n);
- for (int i = 0; i <ans.size(); i++) // 注意先设定好 ans 的 size
- ans[i].resize(n);
- int num = n * n;
- int i = 1;
- int l = 0;
- int r = n - 1;
- int u = 0;
- int d = n - 1;
- while (i <= num) {
- for (int j = l; j <= r && i <= num; i++, j++)
- ans[u][j] = i;
- u++;
- for (int j = u; j <= d && i <= num; i++, j++)
- ans[j][r] = i;
- r--;
- for (int j = r; j>= l && i <= num; i++, j--)
- ans[d][j] = i;
- d--;
- for (int j = d; j>= u && i <= num; i++, j--)
- ans[j][l] = i;
- l++;
- }
- return ans;
- }
- };
来源: http://www.bubuko.com/infodetail-3498753.html