23 August 2010

Project Euler : What is the total of all the name scores in the file of first names?

Problem 22

Using names.txt (right click and 'Save Link/Target As...'), a 46K text file containing over five-thousand first names, begin by sorting it into alphabetical order. Then working out the alphabetical value for each name, multiply this value by its alphabetical position in the list to obtain a name score.
For example, when the list is sorted into alphabetical order, COLIN, which is worth 3 + 15 + 12 + 9 + 14 = 53, is the 938th name in the list. So, COLIN would obtain a score of 938 × 53 = 49714.
What is the total of all the name scores in the file?

Solution (in Ruby)

All we had to do is read the file convert all the values into an array and sort it. Then for each word we need to apply the rule as stated in the problem. If you could look at the code inside the loop, i would be ripping the starting and trailing quotes '"' and then converting them to index numbers. ie A for 1, B for 2 upto Z for 26. Rest is self explanatory.

names = File.new("/names.txt","r").gets.split(/,/).sort
sum = 0
index = 1
names.each do |n|
  sum += n.gsub!(/^"(.*?)"$/,'\1').split(//).inject(0){|b,i| b+i[0]-64} * index
puts "The total of all the name scores is #{sum}"

Hover here to see the solution


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