[SDOI2011]计算器

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YM zky跑得飞快的BSGS

数论模板题,复习下数论

过不了样例都能A是闹哪样啊233

Code:

#include <cstdio>#include <map>#include <cmath>using namespace std;map<long long, long long> s;long long y, z, p, T, k;inline long long exgcd(long long a, long long b, long long &x, long long &y){if(!b){x = 1, y = 0;return a;}else{long long d = exgcd(b, a % b, x, y), t = x;x = y, y = t - a / b * y;return d;}}inline long long quick_pow(long long n, long long m, long long p){long long res = 1;while (m){if (m & 1)res = res * n % p;m >>= 1;n = n * n % p;}return res;}inline void INV(long long a, long long b, long long p){a = quick_pow(a, p-2, p);b = b * a % p;if (!b)puts("Orz, I cannot find x!");elseprintf("%lld\n", b);}inline long long gcd(long long a, long long b){long long t;while(b){t = a % b;a = b;b = t;}return a;}inline long long inv(long long a){if (gcd(a, p) == 1)return quick_pow(a, p-2, p);long long d, x, y;d = exgcd(a, p, x, y);return d == 1 ? (x + p) % p : -1;}inline void BSGS(long long a, long long b, long long p){int i;long long m = sqrt(p) + .5, v = inv(quick_pow(a,m,p)), e = 1;s.clear();s[1] = 0;for(i = 1;i < m; ++i)e = e * a % p, s[e] = i;for(i = 0;i <= m; ++i){if(s.count(b)){printf("%lld\n", i * m + s[b]);return;}b = b * v % p;}puts("Orz, I cannot find x!");}inline void solve(long long type){switch (type){case (1) :{printf("%d\n", quick_pow(y, z, p));break;}case (2) :{INV(y, z, p);break;}case (3) :{BSGS(y, z, p);break;}}}char c;inline void read(long long &x){for (c = getchar();c > '9' || c < '0';c = getchar());for (x = 0;c >= '0' && c <= '9';c = getchar())x = (x << 3) + (x << 1) + c - '0';}int main(){read(T), read(k);while (T--){read(y), read(z), read(p);solve(k);}}

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