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

For example,

Given n = 3,

You should return the following matrix:

[ [ 1, 2, 3 ], [ 8, 9, 4 ], [ 7, 6, 5 ]] 写一个回旋的矩阵

class Solution {public:    vector
     
      
        > generateMatrix(int n) {        vector
       
        
          >re;        for(int i = 0 ;i < n; i++)        {            vector 
         
           temp(n,0);            re.push_back(temp);        }        int direction =0;   //0 right ,1 down ,2 left, 3 up        int length = n;        int x = 0;        int y = 0;        int step = 0;        for(int i = 1 ; i <= n*n ; i++)        {            re[x][y] = i;            step++;            if(step == length)  //should turn            {                direction = (direction + 1)%4;                if(direction == 0)                {                    y = y+1;                    step = 0;                }                else if(direction == 1)                {                    x = x+1;                    length--;                    step = 0;                }                else if(direction == 2)                {                    y = y-1;                    step = 0;                }                else                {                    x = x-1;                    length--;                    step = 0;                }            }            else            {                if(direction == 0) y = y+1;                else if(direction == 1)x = x+1;                else if(direction == 2)y = y-1;                else x = x-1;            }                    }        return re;    }};