0059._Spiral_Matrix_II.md

59. Spiral Matrix II

难度:Medium

刷题内容

原题连接

• https://leetcode.com/problems/spiral-matrix-ii/

内容描述

Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

Example:

Input: 3
Output:
[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

思路1 - 时间复杂度: O(n^2)- 空间复杂度: O(n^2)******

和之前的旋转遍历矩阵一样的方法，只不过这里我们要先分配一个矩阵储存，因为vector数组不好操作。

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        int temp[n][n];
        int range = n,cur = 1;
        for(int i = 0;i < (n + 1) / 2 ;++i)
        {
            for(int j = 0;j < range;++j)
                temp[i][j + i] = cur++;
            for(int j = 1;j < range;++j)
                temp[i + j][i + range - 1] = cur++;
            for(int j = 1;j < range;++j)
                temp[i + range - 1][range + i - 1 -j] = cur++;
            for(int j = 1;j < range - 1;++j)
                temp[range + i - 1 - j][i] = cur++;
            range -= 2;
        }
        vector<vector<int> > ans;
        for(int i = 0;i < n;++i)
        {
            vector<int> v;
            for(int j = 0;j < n;++j)
                v.push_back(temp[i][j]);
            ans.push_back(v);
        }
        return ans;
    }
};