27 August 2010

Project Euler : How many letters would be needed to write all the numbers in words from 1 to 1000?

Problem 17

If the numbers 1 to 5 are written out in words: one, two, three, four, five, then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
If all the numbers from 1 to 1000 (one thousand) inclusive were written out in words, how many letters would be used?

NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and forty-two) contains 23 letters and 115 (one hundred and fifteen) contains 20 letters. The use of "and" when writing out numbers is in compliance with British usage.

Solution (in Ruby)

We will have to first try to come out with the unique words that are present in the numbers. We start with the ones which are one, two upto nine. Then the elevens starting from eleven to nineteen. Then the tens, twenties upto nineties. We should also define a hundred and thousand. After that the logic is directly readable from the ruby code given below.

Hover here to see the solution


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