C++ 解法, 执行用时: 7ms, 内存消耗: 472K, 提交时间: 2021-10-14 22:08:12

#include<bits/stdc++.h>
using namespace std;
long long n, ans, fac[19], su, uc = 1, f;
int a[10];
vector<int>v;
void dfs(int x) {
	if (x == v.size())
		ans += fac[su - 1] * (su - f) / uc;
	else
		for (int i = 1; i <= a[v[x]]; i++) {
			if (!v[x])
				f = i;
			su += i, uc *= fac[i], dfs(x + 1), uc /= fac[i], su -= i;
		}
}
signed main() {
	fac[0] = 1;
	for (int i = 1; i < 19; i++)
		fac[i] = fac[i - 1] * i;
	cin >> n;
	while (n)
		a[n % 10]++, n /= 10;
	for (int i = 0; i < 10; i++)
		if (a[i])
			v.push_back(i);
	dfs(0);
	cout << ans;
}