循环小数 Repeating Decimals

?UVa202

?

?方法：长除法

#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#define maxn 3000
int mer[maxn] = { 0 };//商
int rem[maxn] = { 0 };//余数
int arr[maxn] = { 0 };//标记重复的余数，出现重复代表无限循环小数

int main()
{
	int dived, div;//被除数  除数
	int i = 1;
	int count = 0;//记录循环节大小
	int not_cyc = 1;//标记是否循环
	scanf("%d %d", &dived, &div);
	int a = dived;//第一个被除数
	int b = div;//第一个除数
	int fir_mer = dived / div;//第一个商
	while (dived)//dived为0代表是有限小数
	{
		dived = (dived % div) * 10;//上一个余数*10作为下一个的被除数
		if (rem[dived] == 0)//余数不重复
		{
			rem[dived]++;
			arr[i] = dived;//记录余数
		}
		else//余数重复，说明是无限循环小数
		{
			for (int j = 1; j < i; j++)//遍历寻找重复的余数
			{
				if (arr[j] == dived)//找到了
				{
					count = i - j;//相减得到循环节
					break;
				}
			}
			not_cyc = 0;//表示是否循环
			break;
		}
		mer[i++] = dived / div;//记录商
	}

	if (!not_cyc)//循环进入
	{
		if (count <= 50)
		{
			printf("%d/%d = %d.(", a, b, fir_mer);
			for (int j = 1; j < i; j++)
			{
				printf("%d", mer[j]);
			}
			printf(")\n   ");
			printf("%d = number of digits in repeating cycle\n", count);
		}
		else if (count > 50)
		{
			printf("%d/%d = %d.(", a, b, fir_mer);
			for (int j = 1; j <= 50; j++)
			{
				printf("%d", mer[j]);
			}
			printf("...)\n   ");
			printf("%d = number of digits in repeating cycle\n", count);
		}
	}
	else//不循环
	{
		printf("%d/%d = %d.", a, b, fir_mer);
		for (int j = 1; j < i - 1; j++)
		{
			printf("%d", mer[j]);
		}
		printf("(0)\n   ");
		printf("1 = number of digits in repeating cycle\n");
	}

	return 0;
}