FZU 1752 A^B mod C (快速幂)

Problem 1752 A^B mod C

Accept: 714 Submit: 3084
Time Limit: 1000 mSec Memory Limit : 32768 KB

Problem Description

Given A,B,C, You should quickly calculate the result of A^B mod C. (1<=A,B,C<2^63).

Input

There are multiply testcases. Each testcase, there is one line contains three integers A, B and C, separated by a single space.

Output

For each testcase, output an integer, denotes the result of A^B mod C.

Sample Input

3 2 42 10 1000

Sample Output

124

Source

FZU 2009 Summer Training IV--Number Theory 

题意很简单,求A^BmodC
但是数据范围很大,如果直接快速幂会爆 unsigned long long.
所以在计算快速幂的时候通过二进制计算A*B;

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
typedef unsigned long long LL;
LL mul(LL a,LL b,LL c){
	LL ans = 0,temp = a%c;
	while(b){
	//	cout<<"ans"<=c){
				ans-=c;
			}
	}
			if((temp<<=1)>=c){
				temp-=c;
			}
			b>>=1;
	}
	return ans;
}
LL modPow(LL a,LL b,LL m){
	LL ret = 1;
	while(b){
//		cout<<"ret"<>=1;
	}
	return ret;
}
int main() {

	LL a,b,c;
	while(scanf("%I64d%I64d%I64d",&a,&b,&c)!=EOF){
		LL sum = modPow(a,b,c);
		printf("%I64d\n",sum);
	}
	
	return 0;	
}


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