丑数

/*********************************************************************
题目：我们把只包含因子2、3和5的数称作丑数。求按从小到大的顺序的第1500个
丑数。例如6、8都是丑数，但14不是，因为它包含因子7。习惯上我们把1当做第
一个丑数。
*********************************************************************/
#include<stdio.h>

int Min(int number1, int number2, int number3);
int GetUglyNumber_Solution2(int index)
{
	if(index <= 0)
		return 0;

	int* pUglyNumbers = new int[index];
	pUglyNumbers[0] = 1;
	int nextUglyIndex = 1;

	int* pMultipy2 = pUglyNumbers;
	int* pMultipy3 = pUglyNumbers;
	int* pMultipy5 = pUglyNumbers;

	while(nextUglyIndex < index)
	{
		int min = Min(*pMultipy2 * 2, *pMultipy3 * 3, *pMultipy5 * 5);
		pUglyNumbers[nextUglyIndex] = min;
		
		//使*pMultipy2 * 2 ，*pMultipy3 * 3，*pMultipy5 * 5最接近最小的丑数
		while(*pMultipy2 * 2 <= pUglyNumbers[nextUglyIndex])
			++pMultipy2;
		while(*pMultipy3 * 3 <= pUglyNumbers[nextUglyIndex])
			++pMultipy3;
		while(*pMultipy5 * 5 <= pUglyNumbers[nextUglyIndex])
			++pMultipy5;

		++nextUglyIndex;
	}

	int ugly = pUglyNumbers[nextUglyIndex - 1];
	delete[] pUglyNumbers;
	return ugly;
}

int Min(int number1, int number2, int number3)
{
	int min = (number1 < number2) ? number1 : number2;
	min = (min < number3) ? min : number3;

	return min;
}

void test()
{
	printf("%d\n",GetUglyNumber_Solution2(1500));
}
int main()
{
	test();
	return 0;
}

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