C++ 解法, 执行用时: 2ms, 内存消耗: 424KB, 提交时间: 2021-11-25

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > Matrix(int n) {
        // write code here
        vector<vector<int> > res(n,vector<int>(n));
        int k=1;
        int left=0,right=n-1;
        int up=0,down=n-1;
        while(true) {
            for(int i=left;i<=right;++i) res[up][i]=k++;
            if(++up>down) break;
            for(int i=up;i<=down;++i) res[i][right]=k++;
            if(--right<left) break;
            for(int i=right;i>=left;--i) res[down][i]=k++;
            if(--down<up) break;
            for(int i=down;i>=up;--i) res[i][left]=k++;
            if(++left>right) break;
        }
        return res;
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 308KB, 提交时间: 2022-05-26

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > Matrix(int n) {
        // write code here
        vector<vector<int>> ans(n, vector<int>(n, 0));
        
        int left = 0, right = n - 1, up = 0, down = n - 1;
        int begin = 1, end = n * n;
        while (begin <= end) {
            for (int i = left; i <= right; ++i) {
                ans[up][i] = begin++;
            }
            up++;
            for (int i = up; i <= down; ++i) {
                ans[i][right] = begin++;
            }
            right--;
            for (int i = right; i >= left; --i) {
                ans[down][i] = begin++;
            }
            down--;
            for (int i = down; i >= up; --i) {
                ans[i][left] = begin++;
            }
            left++;
        }
        return ans;
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 384KB, 提交时间: 2022-07-12

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int> > Matrix(int n) {
        // write code here
        int num=1;
        int l1=0,l2=n-1,r1=0,r2=n-1;
        vector<vector<int>>v(n,vector<int>(n));
        while(num<=n*n)
        {
            for(int i=r1;i<=r2;++i)
            {
                v[l1][i]=num;
                ++num;
            }
            if(num>n*n)break;
            ++l1;
            for(int i=l1;i<=l2;++i)
            {
                v[i][r2]=num;
                ++num;
            }
            if(num>n*n)break;
            --r2;
            for(int i=r2;i>=r1;--i)
            {
                v[l2][i]=num;
                ++num;
            }
            if(num>n*n)break;
            --l2;
            for(int i=l2;i>=l1;--i)
            {
                v[i][r1]=num;
                ++num;
            }
            if(num>n*n)break;
            ++r1;
        }
        return v;
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 384KB, 提交时间: 2022-03-14

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return int整型vector<vector<>>
     */
    vector<vector<int>> Matrix(int n) {
    vector<vector<int>> ans(n,vector<int>(n,0));
    int top=0,bottom=n-1,left=0,right=n-1,count=1;
    while(top<=bottom&&left<=right)
    {
        for(int j=left;j<=right;j++)
        {
            ans[top][j]=count;
            count++;
        }
        for(int i=top+1;i<=bottom;i++)
        {
            ans[i][right]=count;
            count++;
        }
        if(left<right&&top<bottom)
        {
            for(int j=right-1;j>=left;j--)
            {
                ans[bottom][j]=count;
                count++;
            }
            for(int i=bottom-1;i>top;i--)
            {
                ans[i][left]=count;
                count++;
            }
        }
        left++;right--;top++;bottom--;
    }
        return ans;
    }
};

C++ 解法, 执行用时: 3ms, 内存消耗: 384KB, 提交时间: 2021-11-26

class Solution {
public:
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param n int整型 
     * @return int整型vector<vector<>>
     */
    int M[22][22];
    int dx[4] = {-1, 0, 1, 0};
    int dy[4] = {0, 1, 0, -1};
    vector<vector<int> > Matrix(int n) {
        // write code here
        vector<vector<int> > matrix;
        memset(M,-1,sizeof M);
        f(0,0,1,n,1);
        for(int i = 0 ; i < n ; i ++)
        {
            vector<int> temp;
            for(int j = 0 ; j < n ; j ++)
            {
               temp.push_back(M[i][j]);
            } 
            matrix.push_back(temp);
        }
         return matrix;
    }
    
    void f(int x,int y,int num,int n,int d){
        for (int k = 0; k < n * n; k ++ )
        {
            M[x][y] = num++;
            int a = x + dx[d], b = y + dy[d];
            if (a < 0 || a >= n || b < 0 || b >= n || M[a][b] != -1)
            {
                d = (d + 1) % 4;
                a = x + dx[d], b = y + dy[d];
            }
            x = a, y = b;
        }
    }
};