| Problem 136 - Ugly Numbers, Explanations |
Ugly numbers, ugly algorithm right? There's no entry, so we can precalculate at home!
As long as possible divide each number by 2, 3 and 5. If you eventually get to 1, this number is ugly.
You guessed it : my ugly algorithm doesn't make it within the time limit! But, you can calculate at home, so there's no problem with this!
If you are in trouble with the multi-entry input, read my how to read input.
I'm no fool!
Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, ...
shows the first 11 ugly numbers. By convention, 1 is included.
Write a program to find and print the 1500'th ugly number.
There is no input to this program. Output should consist of a single line as shown below, with <number> replaced by the number computed.
The 1500'th ugly number is <number>.