# BZOJ 2242 [SDOI2011]计算器 | BSGS

insert的时候忘了取模了……

#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
typedef long long ll;
#define enter putchar('\n')
#define space putchar(' ')
template <class T>
char c;
bool op = 0;
while(c = getchar(), c > '9' || c < '0')
if(c == '-') op = 1;
x = c - '0';
while(c = getchar(), c >= '0' && c <= '9')
x = x * 10 + c - '0';
if(op) x = -x;
}
template <class T>
void write(T x){
if(x < 0) putchar('-'), x = -x;
if(x >= 10) write(x / 10);
putchar('0' + x % 10);
}
const int P = 999979, N = 100005;
ll T, K, A, B, C;
ll adj[P], nxt[N], num[N], val[N], stk[N], top;
ll qpow(ll a, ll x, ll p){
ll ret = 1;
while(x){
if(x & 1) ret = ret * a % p;
a = a * a % p;
x >>= 1;
}
return ret;
}
ll gcd(ll a, ll b){
return b ? gcd(b, a % b) : a;
}
void exgcd(ll a, ll b, ll &x, ll &y){
if(!b) return (void)(x = 1, y = 0);
exgcd(b, a % b, y, x);
y -= a / b * x;
}
ll inv(ll a, ll p){
ll x, y;
exgcd(a, p, x, y);
return (x % p + p) % p;
}
void clear(){
}
void insert(ll x, ll y){
stk[++top] = x % P;
num[top] = x, val[top] = y;
}
ll find(ll x){
for(int i = adj[x % P]; i; i = nxt[i])
if(num[i] == x) return val[i];
return -1;
}
bool force(){
A %= C, B %= C;
ll sum = 1 % C;
for(ll i = 0; i <= 30; i++, sum = sum * A % C)
if(sum == B) return write(i), enter, 1;
return 0;
}
void bsgs(){
clear();
ll D = 1, sum = 1 % C, cnt = 0, n = sqrt(C), m = ceil(C / n);
for(ll g = gcd(A, C); g > 1; g = gcd(A, C)){
if(B % g) return (void)puts("Orz, I cannot find x!");
C /= g, B /= g, D = D * A / g % C, cnt++;
}
B = B * inv(D, C) % C;
for(ll i = 1; i <= m; i++)
sum = sum * A % C, insert(sum * B % C, i);
for(ll i = 1, tot = 1; i <= n; i++){
ll y = find(tot = tot * sum % C);
if(y != -1) return (void)(write(i * m - y + cnt), enter);
}
puts("Orz, I cannot find x!");
}
int main(){
while(T--){
if(K == 1) write(qpow(A, B, C)), enter;
else if(K == 2){
ll x, y, g = gcd(A, C);
if(B % g){
puts("Orz, I cannot find x!");
continue;
}
exgcd(A, C, x, y);
x *= B / g;
write((x % (C / g) + (C / g)) % C/g), enter;
}
else bsgs();
}
return 0;
}


posted @ 2017-12-27 15:18  胡小兔  阅读(179)  评论(0编辑  收藏  举报