剑指Offer32 丑数

/*************************************************************************
> File Name: 32_UglyNumber.c
> Author: Juntaran
> Mail: JuntaranMail@gmail.com
> Created Time: 2016年09月02日 星期五 12时29分59秒
************************************************************************/

#include <stdio.h>
#include <malloc.h>

int isUgly(int number)
{
while (number % 2 == 0)
number /= 2;
while (number % 3 == 0)
number /= 3;
while (number % 5 == 0)
number /= 5;

return (number==1) ? 0 : -1;
}

// 低效方法
int getUglyNumber1(int n)
{
if (n <= 0)
return -1;

int number = 0;
while (n != 0)
{
++ number;
if (isUgly(number) == 0)
n --;
}
printf("%d\n", number);
return number;
}

int MinOfThree(int a, int b, int c)
{
int minNum = a>b ? b : a;
minNum = minNum>c ? c : minNum;
return minNum;
}

// 高效方法 空间换时间
int getUglyNumber2(int index)
{
if (index <= 1)
return index;

int* ugly = (int*)malloc(sizeof(int) * index);
int i2 = 0;
int i3 = 0;
int i5 = 0;
ugly[0] = 1;

for (int i = 1; i < index; ++i)
{
int temp2 = ugly[i2] * 2;
int temp3 = ugly[i3] * 3;
int temp5 = ugly[i5] * 5;

int minNum = MinOfThree(temp2, temp3, temp5);
ugly[i] = minNum;

if (minNum == temp2)
i2 ++;
if (minNum == temp3)
i3 ++;
if (minNum == temp5)
i5 ++;
}
printf("%d\n", ugly[index - 1]);
return ugly[index - 1];
}

int main()
{
getUglyNumber1(1500);
getUglyNumber2(1500);
}