Submission #860472

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Source Code Expand

#include <iostream>
using namespace std;

typedef long long ll;
ll n, s, b;

ll f(ll b, ll n){
	ll res = 0;
	while(n >= b){
		res += n % b;
		n = n / b;
		if(res > s) return -1;
	}
	res += n;
	return res;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin >> n >> s;

	for(b=2; b*b<=n; b++){
		if(f(b, n) == s){
			cout << b << endl;
			return 0;
		}
	}
	ll p = b;

	for(; p>0; p--){
		b = 1 + (n-s) / p;
		if(0 <= p && p < b && s-b < p && p <= s){
			cout << b << endl;
			return 0;
		}
	}

	if(n==s){
		cout << n << endl;
		return 0;
	}

	cout << -1 << endl;

	return 0;
}

Submission Info

Judge Result