剑指Offer32 丑数

 /*************************************************************************
     > File Name: 32_UglyNumber.c
     > Author: Juntaran
     > Mail: [e-mail]
     > 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 %  == )
         number /= ;
     while (number %  == )
         number /= ;
     while (number %  == )
         number /= ;

     return (number==) ?  : -;
 }

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

     int number = ;
     while (n != )
     {
         ++ number;
         if (isUgly(number) == )
             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 <= )
         return index;

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

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

         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 - ]);
     return ugly[index - ];
 }

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