保留几位小数笔记

#include <iostream>
using namespace std;
const int N = 20;
int arr[N][N];//0
int main() {
	int n;
	cin >> n; //1~
	int x = 0;
	int y = n;
	arr[1][y] = 0;
	int snake = 1; //爬的距离
	while (snake <= n * n) {
		//往下爬
		while (arr[x + 1][y] == 0 && x + 1 <= n) { //可不可以往下爬
			//arr[x][y]==0 等于没爬过
			//x+1<=n 超过n行
			x += 1;
			arr[x][y] = snake;
			snake += 1;
			//if(snake > n * n) break;
		}
		//break;

		//往左爬
		while (arr[x][y - 1] == 0 && y - 1 >= 1) { //可不可以往下爬
			//arr[x][y]==0 等于没爬过
			//x+1<=n 超过n行
			y -= 1;
			arr[x][y] = snake;
			snake += 1;
		}
		//往上爬
		while (arr[x - 1][y] == 0 && x - 1 >= 1) { //可不可以往下爬
			//arr[x][y]==0 等于没爬过
			//x+1<=n 超过n行
			x -= 1;
			arr[x][y] = snake;
			snake += 1;
		}
		//往右爬
		while (arr[x][y+1] == 0 && y + 1 <= n) { //可不可以往下爬
			//arr[x][y]==0 等于没爬过
			//x+1<=n 超过n行
			y += 1;
			arr[x][y] = snake;
			snake += 1;
		}
		
	}
	for (int i = 1; i <= n; i++) {
		//TODO
		for (int j = 1; j <= n; j++) {
			cout << arr[i][j] << " ";//
		}
		cout << endl;
	}
	return 0;
}