algorithms and Data structures examples

algorithms.rb

def find_index(numbers, number)
    numbers.each_with_index do |n, i|
        if n == number
            return i
        end
    end

    return nil
end


def find_sum_pairs(numbers, sum)
    cache = {}

    numbers.each_with_index do |n, i|
        target = sum - n
        if cache.has_key?(target)
            return i, cache[target]
        end

        cache[n] = i
    end

    return nil
end



def find_index_sorted(numbers, number)

    middle = numbers.size / 2
    first = 0
    last = numbers.size - 1

    while middle != last && middle != first

        if numbers[middle] == number
            return middle
        end

        puts "middle is #{middle}"
        puts "first is #{first}"
        puts "last is #{last}"
        gets

        if number > numbers[middle]
            first = middle
            middle += (last - middle) / 2
        else
            last = middle
            middle = middle / 2
        end
    end

    return nil
end

# numbers = (1..1000000).step(1).to_a
# number = 1100
# puts find_index_sorted(numbers, number).inspect


def divide(number, divisor)

    results = 0

    while number >= divisor
        number -= divisor
        result += result
        divisor += divisor
    end

    remainder = number
    return result, remainder
end

require 'pry'


def find_common_rhyme
    words = File.open('/usr/share/dict/words').read

    rhymes = Hash.new { [] }

    most = 0
    common_rhyme = nil

    words.each_line do |word|
        word = word.strip.downcase

        rhyme = word[-3..-1]
        rhymes[rhyme] <<= word

        if rhymes[rhyme].size > most
            most = rhymes[rhyme].size
            common_rhyme = rhyme
        end
    end

    puts common_rhyme
    puts rhymes[common_rhyme].inspect
    puts rhymes[common_rhyme].size
end