Wins the offer - 51 Number ugly

Title Description

It contains only the number of prime factors 2, 3 and 5 is referred to as the number of ugly (Ugly Number). E.g. 6,8 are several ugly, but not 14, because it contains seven prime factors. Traditionally we have 1 as the first ugly number. Seeking ascending through N ugly large number sequence.

 

　　

1  // Use traverse determination method 
2  class Solution01 {
 . 3  public :
 . 4      int GetUglyNumber_Solution ( int index) {
 . 5          IF (index < 1 ) return  0 ;
 . 6          int CNT = 0 ;
 . 7          for ( int I = 1 ; CNT <index ; ++ I)
 . 8          {
 . 9              IF (isChouShu (I))
 10                  CNT ++ ;
 . 11              IF (CNT == index)
12                  return i;
13          }
 14      }
 15      bool isChouShu ( int num)
 16      {
 17          while (in% 2 == 0 )
 18              a / = 2 ;
19          while (in% 3 == 0 )
 20              a / = 3 ;
21          while (in% 5 == 0 )
 22              a / = 5 ;
23          return== NUM . 1 ;
 24      }
 25  };
 26 is  
27  
28  // use the stored data Method 
29  class Solution02 {
 30  public :
 31 is      int GetUglyNumber_Solution ( int index) {
 32          IF (index < . 1 ) return  0 ;
 33 is          Vector < int > V (index, 0 );
 34 is          V [ 0 ] = . 1 ;
 35          int P2, P3, P5, K = . 1 ;
 36         p2 = p3 = p5 = 0 ;
37          while (k < index)
 38          {
 39              v [k ++] = min ( min (v [p2] * 2 , v [p3] * 3 ), v [p5] * 5 );
40              The while (v [p2] * 2 <= v [k - 1 ]) p2 ++ ;
41              while (v [p3] * 3 <= v [k - 1 ]) ++ p3 ;
42              The while (v [p5] * 5 <= v [k - 1 ]) p5 ++ ;
43          }
 44          return v[index - 1];
45     }
46 };