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
", 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
", ugly[index - 1]);
    return ugly[index - 1];
}

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