Add minimum coins.

minimum_coins.rb

@@ -0,0 +1,9 @@
+def minimum_coins(number)
+  minimum = 0
+  [100, 50, 25, 10, 5, 1].each do |denom|
+    return minimum if number == 0
+    minimum += number / denom
+    number %= denom
+  end
+  minimum
+end

ruby-kata-minimum-coins.md

@@ -0,0 +1,9 @@
+Write a method `def minimum_coins(number)` which takes a number as an argument (ranging from 1 to 250) and returns the minimum number of coins needed to calculate `number`. Coins here represent the following values: 1, 5, 10, 25, 50 and 100. Consider the following examples:
+
+* The minimum number of coins to generate `35` would be 2: 10 and 25.
+* The minimum number of coins to generate `37` would be 4: 1, 1, 10, 25.
+* The minimum number of coins to generate `101` would be 2: 1 and 100.
+
+Notes:
+
+* Do the assignment with TDD if you want some TDD practice (you likely will need another file in addition to `code.rb` for your test suite if you choose to do this)!

spec/_spec.rb

@@ -1,5 +1,6 @@
 require_relative '../caesar_cipher'
 require_relative '../duplicate_element_counter'
+require_relative '../minimum_coins'
 require_relative '../minimum_consecutive_integers'
 require_relative '../optimal_guesser'
 require_relative '../palindrome'
@@ -85,6 +86,14 @@
   end
 end
 
+describe '#minimum_coins' do
+  it 'returns the minimum number of coins needed' do
+    expect(minimum_coins(35)).to eq 2
+    expect(minimum_coins(37)).to eq 4
+    expect(minimum_coins(101)).to eq 2
+  end
+end
+
 describe '#palindrome?' do
   it 'correctly determines if a string is a palindrome' do
     expect(palindrome?('A Santa at NASA')).to eq true