【leetcode】Spiral Matrix II

Spiral Matrix II

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 ]
]

 

与Spiral Matrix类似：

 

class Solution {
public:
    vector<vector<int> > generateMatrix(int n) {
       
        int x1=0;
        int y1=0;
        int x2=n-1;
        int y2=n-1;
       
        int count=0;
        vector<vector<int>> result(n,vector<int>(n));
        while(count<n*n)
        {
           
            for(int j=y1;j<=y2;j++)
            {
                count++;
                result[x1][j]=count;
            }              
            for(int i=x1+1;i<=x2;i++)
            {
                count++;
                result[i][y2]=count;
            }
           
            for(int j=y2-1;j>=y1;j--)
            {
                count++;
                result[x2][j]=count;
            }
           
            for(int i=x2-1;i>x1;i--)
            {
                count++;
                result[i][x1]=count;
            }
           
            x1++;y1++;x2--;y2--;
        }
       
        return result;
       
       
    }
};