[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 ]
]

和上一题Spiral Matrix一个道理，同样的方法遍历，然后复制就OK，很好理解。

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