LeetCode： Two Sum II - Input array is sorted

Question

Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

Your returned answers (both index1 and index2) are not zero-based. You may assume that each input would have exactly one solution and you may not use the same element twice.

Example 1:

Input: numbers = [2,7,11,15], target = 9

Output: [1,2]

Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.

Example 2:

Input: numbers = [2,3,4], target = 6

Output: [1,3]

Example 3:

Input: numbers = [-1,0], target = -1

Output: [1,2]

Solution

def two_sum(numbers, target)
  dict = {}

  numbers.each_with_index do |number, i|
    if dict[target-number]
      return dict[target - number]+1, i+1
    end
    dict[number] = i
  end
end