A bit of classic

#include<bits/stdc++.h>

const int INF  = 0x3f3f3f3f;
const int Maxn = 255;

#define ll long long
#define mem(x,y) memset(x,y,sizeof(x))
using namespace std;
int mp[Maxn][Maxn], cnt = 0, flag = 0;
int mx[8] = {2, 2, 1, 1, -2, -2, -1, -1}, my[8] = {1, -1, 2, -2, 1, -1, 2, -2};

int door(int x, int y, int n) {  //  计算(x,y)下一步能跳的位置数
    int cnt = 0;
    for (int i = 0; i < 8; i++) {
        int a = x + mx[i], b = y + my[i];
        if (a >= 1 && a <= n && b >= 1 && b <= n && mp[a][b] == 0)
            cnt++;
    }
    return cnt;
}
void deal(int n) {
    if (n > 1 && n < 5) return;
    cnt = flag = 0;

    for (int tt = 1; tt <= 8; tt++)
        for (int xx = 1; xx <= 6; xx++) {

            int x = tt, y = xx;
            mem(mp, 0);
            for (cnt = 1; cnt <= n * n; cnt++) {
                mp[x][y] = cnt;
                if (cnt == n * n) {
                    flag = 1;
                    return;
                }
                if (door(x, y, n) == 0)
                    break;
                int m = 10, a, b;

                for (int i = 0; i < 8; i++) {  // 贪心
                    int p = x + mx[i], q = y + my[i];
                    if (!(p >= 1 && p <= n && q >= 1 && q <= n && mp[p][q] == 0)) continue;
                    int k = door(p, q, n);
                    if (k < m) {
                        m = k;
                        a = p, b = q;
                    }

                }
                x = a, y = b;
            }

        }
}
int main() {
    freopen("classic.in", "r", stdin);
    freopen("classic.out", "w", stdout);
    int N;
    while (cin >> N) {
        deal(N);
        if (flag == 0)
            printf("No solution.
");
        else {
            printf("There is solution:
");
            for (int i = 1; i <= N; i++)
                for (int j = 1; j <= N; j++)
                    printf("%d%c", mp[i][j], j == N ? '
' : ' ');
        }
    }
}