力扣螺旋矩阵2 java 执行时间100%用户

class Solution {
    public int[][] generateMatrix(int n) {
        int[][] s = new int[n][n];
        int x = 0;
        int y = 0;
        int max = n - 1;
        boolean xt = true;
        boolean yt = true;
        for(int i = 1;i <= n*n;i++){
            s[y][x] = i;
            if(xt != yt){
                if(yt){
                    y++;
                    if(y >= max || s[y+1][x] != 0){
                        yt = !yt;
                    }
                }else{
                    y--;
                    if(y <= 0||s[y-1][x] != 0){
                        yt = !yt;
                    }
                }
            }else{
                if(xt){
                    x++;
                    if(x >= max || s[y][x+1] != 0){
                        xt = !xt;
                    }
                }else{
                    x--;
                    if(x <= 0||s[y][x-1] != 0){
                        xt = !xt;
                    }
                }
            }
        }
        return s;
    }
}