Commit e9a585e

@@ -0,0 +1,30 @@
+require 'spec_helper'
+description = <<-PROBLEM
+Given an array of integers,
+return indicies of the two numbers such that they add up to a specific target.
+PROBLEM
+
+describe description do
+  def two_sum(numbers, target:)
+    items = {}
+    numbers.each_with_index do |number, index|
+      next if number > target
+      if other_index = items[target - number]
+        return [index, other_index].sort
+      end
+      items[number] = index
+    end
+  end
+
+  it 'returns 2 + 7' do
+    numbers = [2, 7, 11, 15]
+    results = two_sum(numbers, target: 9)
+    expect(results).to eql([0, 1])
+  end
+
+  it 'returns 2 + 4' do
+    numbers = [3, 2, 4]
+    results = two_sum(numbers, target: 6)
+    expect(results).to eql([1, 2])
+  end
+end