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hdu 2814 Interesting Fibonacci
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题目大意:就是给你两个函数,一个是F(n) = F(n-1) + F(n-2),
F(0) = 0, F(1) = 1;
还有一个是 G(n) = G(n-1)^F(a^b);
G(1) = F(a^b);
求G(n) % c;
范围:A, B, N, C (10<=A, B<2^64, 2<=N<2^64, 1<=C<=300)
注意了:c的范围是1<= C <= 300,所以说它一定会有循环 节:
解题思路: 首先算G(1) = F(a^b),设a^b的循环节是len;
F(a^b)%c = F(a^b%len)%c;
一边加一边取余
然后算G(n)%c = F(a^b)^(F(a^b)^(n-1)) % c;
G(n)%c = F(a^b)^(F(a^b)^(n-1)%phi(c)+phi(c))%c;
F(a^b)^(n-1)%phi(c)+phi(c) == (F(a^b)%phi(c)^(n-1))+phi(c)
F(a^b)%phi(c) 有循环节。同上,详细详见代码
上代码:
/*
2015 - 8 - 16 下午
Author: ITAK
今日的我要超越昨日的我,明日的我要胜过今日的我,
以创作出更好的代码为目标,不断地超越自己。
*/
#include <iostream>
#include <cstdio>
using namespace std;
//高速幂取余
int quick_mod(int a, unsigned long long b, int c)
{
int ans = 1;
a %= c;
while(b)
{
if(b & 1)
ans = (ans*a) % c;
b >>= 1;
a = (a*a) % c;
}
return ans;
}
//欧拉函数
int Phi(int m)
{
int ans = m;
for(int i=2; i*i<=m; i++)
{
if(m%i == 0)
ans -= ans/i;
while(m%i == 0)
m /= i;
}
if(m > 1)
ans -= ans/m;
return ans;
}
//公式:x^y % c == x^(y%phi(c)+phi(c))%c;
int data[90005],data1[90005];
int main()
{
//注意不要用long long,用unsigned long long
unsigned long long a, b, n;
int c, c1, t, n1, n2, tmp;
int g[10], len=0, len_c=0, len_e=0;
scanf("%d",&t);
for(int k=1; k<=t; k++)
{
//cin>>a>>b>>n>>c;
scanf("%lld%lld%lld%d",&a,&b,&n,&c);
if(c == 1)
{
printf("Case %d: 0\n",k);
continue;
}
data[0]=0, data[1]=1;
data1[0]=0, data1[1]=1;
for(int i=2; i<90005; i++)
{
data[i] = (data[i-1]+data[i-2])%c;
if(data[i]==1 && data[i-1]==0)
{
len = i-1;//c的循环节
break;
}
}
c1 = Phi(c);
if(c1 > 1)
{
for(int i=2; i<90005; i++)
{
data1[i] = (data1[i-1]+data1[i-2])%c1;
hdu 2814 Interesting Fibonacci