Leetcode 题解-59题

• 思路主要参考了代码随想录，自己复现了一遍

class Solution {
    public int[][] generateMatrix(int n) {
        int[][] res = new  int[n][n];

        int startx = 0;
        int starty = 0;
        int mid = n / 2;
        int loop = n / 2;
        int count = 1;
        int off = 1;
        int i, j;

        while (loop > 0) {
            i = startx;
            j = starty;

            for (; j < starty + n - off; j++) { //从左往右，填充（starty+n-off）次 
                res[startx][j] = count++;
            }

            for (; i < startx + n - off; i++) { //从上往下，填充（startx+n-x）次
                res[i][j] = count++ ;
            }

            for (; j > starty; j--) { //从右往左，填充（j-starty）次
                res[i][j] = count++;
            }

            for (; i > startx; i--) { //从下往上，填充（i-startx）次
                res[i][j] = count++;
            }

            loop --; //圈数减一
            startx ++;
            starty ++;
            off += 2; //每填充完一圈，单列填充减少2次！
        }

        if (n % 2 == 1) { //奇数额外填充数字
            res [mid][mid] = count;
        }

        return res;   
    }
}