python/TangDou/LuoGuBook/P5731.cpp

#include <bits/stdc++.h>

using namespace std;
const int N = 10;
int a[N][N];
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int n;
int main() {
    cin >> n;
    //出发点
    int x = 0, y = 0;
    a[0][0] = 1;
    int dir = 0; //方向
    for (int i = 2; i <= n * n; i++) {
        //下一个位置，优先尝试当前方向的下一个位置，也可能不行
        int nx = x + dx[dir], ny = y + dy[dir];//下一个位置不能出界，不能走过
        if (nx == n || nx < 0 || ny == n || ny < 0 || a[nx][ny])
            dir = (dir + 1) % 4;//终于找对了前进方向，走之~
        x += dx[dir], y += dy[dir], a[x][y] = i;
    }//输出结果
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++)
            printf("%3d", a[i][j]);
        printf("\n");
    }
    return 0;
}