Number of Ones

2進数表記の際に1bitsとなる位の数。

設問

Write a program to determine the number of 1 bits in the internal representation of a given integer.

Input sample:

The first argument will be a text file containing an integer, one per line. e.g.

10
22
56

Output sample:

Print to stdout, the number of ones in the binary form of each number.
e.g.

2
3
3

やってみた

#!/usr/bin/env ruby
ARGF.lines do |line|
  puts line.to_i.to_s(2).count('1')
end