ex_BSGS

Posted 2021-02-13 eterna-king

//author Eterna
#define Hello the_cruel_world!
#pragma GCC optimize(2)
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
#include<cstring>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<utility>
#include<cmath>
#include<climits>
#include<deque>
#include<functional>
#include<complex>
#include<numeric>
#include<unordered_map>
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))
#define Pi acos(-1.0)
#define ABS(x) ((x) >= 0 ? (x) : (-(x)))
#define pb(x) push_back(x)
#define lowbit(x) (x & -x)
#define FRIN freopen("C:\Users\Administrator.MACHENI-KA32LTP\Desktop\in.txt", "r", stdin)
#define FROUT freopen("C:\Users\Administrator.MACHENI-KA32LTP\Desktop\out.txt", "w", stdout)
#define FAST ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define outd(x) printf("%d
", x)
#define outld(x) printf("%lld
", x)
#define il inline
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
const int maxn = 1e5;
const int INF = 0x7fffffff;
const int mod = 1e9 + 7;
const double eps = 1e-7;
inline int read_int() {
	char c;
	int ret = 0, sgn = 1;
	do { c = getchar(); } while ((c < ‘0‘ || c > ‘9‘) && c != ‘-‘);
	if (c == ‘-‘) sgn = -1; else ret = c - ‘0‘;
	while ((c = getchar()) >= ‘0‘ && c <= ‘9‘) ret = ret * 10 + (c - ‘0‘);
	return sgn * ret;
}
inline ll read_ll() {
	char c;
	ll ret = 0, sgn = 1;
	do { c = getchar(); } while ((c < ‘0‘ || c > ‘9‘) && c != ‘-‘);
	if (c == ‘-‘) sgn = -1; else ret = c - ‘0‘;
	while ((c = getchar()) >= ‘0‘ && c <= ‘9‘) ret = ret * 10 + (c - ‘0‘);
	return sgn * ret;
}
map <int, int> mp;
il int gcd(int a, int b) {
	return b ? gcd(b, a % b) : a;
}
il int Quick_pow(ll base, ll index, int p) {
	ll res = 1;
	while (index) {
		if (index & 1)res = res * base % p;
		base = base * base % p;
		index >>= 1;
	}
	return res % p;
}
il int EX_BSGS(int a, int b, int p) {
	if (b == 1) return 0;
	mp.clear();
	int cnt = 0, t = 1, s, x, m;
	for (int d = gcd(a, p); d != 1; d = gcd(a, p)) {
		if (b % d) return -1;
		++cnt, b /= d, p /= d, t = 1LL * t * a / d % p;
		if (b == t) return cnt;
	}
	s = b, m = sqrt(p) + 1;
	for (int i = 0; i < m; ++i) {
		mp[s] = i;
		s = 1LL * s * a % p;
	}
	x = Quick_pow(a, m, p), s = t;
	for (int i = 1; i <= m; ++i) {
		s = 1LL * s * x % p;
		if (mp.count(s)) return i * m - mp[s] + cnt;
	}
	return -1;
}
int a, b, p;
int main()
{
	while (scanf("%d %d %d", &a, &p, &b) && a + b + p) {
		a %= p, b %= p;
		int res = EX_BSGS(a, b, p);
		if (res == -1)puts("No Solution");
		else outd(res);
	}
	return 0;
}