BSGS模板(慢速)

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;
}
inline ll Quick_pow(ll a, ll b, int p) {
	ll res = 1;
	while (b) {
		if (b & 1) (res *= a) %= p;
		(a *= a) %= p;
		b >>= 1;
	}
	return res;
}
ll extend_gcd(ll a, ll b, ll& x, ll& y) {
	ll d = a;
	if (b != 0) {
		d = extend_gcd(b, a % b, y, x);
		y -= (a / b) * x;
	}
	else x = 1, y = 0;
	return d;
}
map<ll, int> mp;
int BSGS(ll y, ll z, ll p) {
	if (y == 0 && z == 0) return 1;
	if (y == 0 && z != 0) return -1;
	int m = sqrt(p);
	mp.clear();
	int t = z % p;
	mp[t] = 0;
	for (int j = 1; j <= m; j++) {
		t = t*y%p;
		mp[t] = j;
	}
	t = 1;
	ll mi = Quick_pow(y, m, p), x;
	for (int i = 1; i*i <= p + 1; i++) {
		t = t * mi % p;
		if (mp.count(t)) {
			x = i*m - mp[t];
			return (x % p + p) % p;
		}
	}
	return -1;
};