Project Euler：Problem 26 Reciprocal cycles

标签：c++   project euler   

A unit fraction contains 1 in the numerator. The decimal representation of the unit fractions with denominators 2 to 10 are given:

1/2	=	0.5
1/3	=	0.(3)
1/4	=	0.25
1/5	=	0.2
1/6	=	0.1(6)
1/7	=	0.(142857)
1/8	=	0.125
1/9	=	0.(1)
1/10	=	0.1

Where 0.1(6) means 0.166666..., and has a 1-digit recurring cycle. It can be seen that ¹/₇ has a 6-digit recurring cycle.

Find the value of d < 1000 for which ¹/_d contains the longest recurring cycle in its decimal fraction part.

#include <iostream>
#include <string>
using namespace std;

int rc(int n, int d)
{
	int a[10010];       //记录每一次除法的被除数
	int b[10010];
	memset(a, 0, sizeof(a));
	memset(b, 0, sizeof(b));
	int count = 0;
	while (n%d != 0)
	{
		while (n < d)
			n = n * 10;
		int tmp = n / d;
		count++;
		if (a[n] == 1)
			return count - b[n];
		a[n] = 1;
		b[n] = count;   //最近的一次被除数为n时的位置
		n = n - tmp*d;
	}
	return 0;
}

int main()
{
	int maxlen = 0, maxn = 0;
	for (int i = 1; i < 1000; i++)
	{
		int tmp = rc(1, i);
		if (tmp>maxlen)
		{
			maxn = i;
			maxlen = tmp;
		}
	}
	cout << maxn << endl;
	system("pause");
	return 0;
}

Project Euler：Problem 26 Reciprocal cycles

标签：c++   project euler   

原文地址：http://blog.csdn.net/youb11/article/details/46324491