leetcode 59.螺旋矩阵2

class Solution {
    public:
        vector<vector<int>> generateMatrix(int n) {
            
            int loop=n/2;
            int offset=1;
            int count=1;
            int mid=n/2;
            int i,j;
            int startx=0;
            int starty=0;
            vector<vector<int>> result(n,vector<int>(n,0));
            while(loop--){
                i=startx;
                j=starty;
                for(;j<n-offset;j++){
                    result[i][j]=count++;
                }
                for(;i<n-offset;i++){
                    result[i][j]=count++;
                }
                for(;j>startx;j--){
                    result[i][j]=count++;

                }
                for(;i>starty;i--){
                    result[i][j]=count++;
                }
                startx++;
                starty++;
                offset++;
            }
            if(n%2){
                result[mid][mid]=count;
            }
            return result;
        }
    };