【bzoj2480】Mod 扩展大步小步

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <map>
#define Rep(i, x, y) for (int i = x; i <= y; i ++)
#define Dwn(i, x, y) for (int i = x; i >= y; i --)
#define RepE(i, x) for(int i = pos[x]; i; i = g[i].nex)
using namespace std;
typedef long long LL;
map<LL, int> m1;
int a, b, p, ans;
int Pow(LL x, int y, int m) {
LL z = 1;
while (y) {
if (y & 1) (z *= x) %= m;
y >>= 1, (x *= x) %= m;
}
return z;
}
LL gcd(LL x, LL y) { return !y ? x : gcd(y, x % y); }
int Baby_step_gaint_step() {
a %= p, b %= p, m1.clear();
int k0 = 0; LL t = 1, k;
while ((k = gcd(a, p)) > 1) {
if (b % k != 0) return -1;
p /= k, b /= k, t = (t * a / k) % p; k0 ++;
if (b == t) return k0;
}
int u = sqrt(p) + 1;
LL x = 1, z, num, z0;
Rep(i, 1, u) { LL p1 = x * b % p;
m1[p1] = i, x = a * x % p;
}
z = x * t % p, z0 = x, num = u;
Rep(i, 1, u) {
if (m1[z]) return num - m1[z] + k0 + 1;
z = z * z0 % p, num += u;
}
return -1;
}
int main()
{
while (scanf ("%d%d%d", &a, &p, &b) != EOF) {
if (!a && !b && !p) break ;
ans = 0; LL x = 1;
while (x != b && ans <= 32) x = x * a % p, ans ++;
if (x != b) ans = Baby_step_gaint_step();
if (ans == -1) puts("No Solution");
else printf("%d\n", ans);
}

return 0;
}