新疆大学ACM-ICPC程序设计竞赛五月月赛(同步赛)--B-杨老师的游戏

#include<iostream>
#include<cstring> 
#include<string>
#include<algorithm> 
#include<vector> 
#include<stack> 
#include<bitset>
#include<cstdio> 
#include<cstdlib> 
#include<cmath> 
#include<set> 
#include<list> 
#include<deque> 
#include<map> 
#include<queue>
using namespace std;
typedef unsigned long long ll;
const double PI = acos(-1.0);
const double eps = 1e-6;
const int INF = 998244353;
bool flag[10];
int que[10];
int ans, num;
void judge() {
    int Li, Lk, Lj, di, dj, i;
    for (di = 1; di < 9; ++di) {
        Li = 0;
        for (i = 1; i <= di; ++i) {
            Li = Li * 10 + que[i];
        }
        for (dj = 1; di + dj < 9; ++dj) {
            Lj = 0;
            for (i = di + 1; i <= di + dj; ++i) {
                Lj = Lj * 10 + que[i];
            }
            Lk = 0;
            for (i = di + dj + 1; i < 10; ++i) {
                Lk = Lk * 10 + que[i];
            }
            if (Li * Lj - Lk == num) {
                ++ans;
            }
        }
    }
}

void dfs(int number) {
    if (number > 9) {
        judge();
    }
    int i;
    for (i = 1; i < 10; ++i) {
        if (!flag[i]) {
            flag[i] = true;
            que[number] = i;
            dfs(number + 1);
            flag[i] = false;
        }
    }
}

int main()
{
    cin >> num;
    dfs(1);
    cout << ans << endl;
    return 0;
}