2 Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution.

Example:

nums = [2, 7, 11, 15] target = 9

returns

[0, 1]

because nums[0] + nums[1] = 2 + 7 = 9.

UPDATE (2016/2/13): The return format had been changed to zero-based indices. Please read the above updated description carefully.

Python

def twoSum(nums, target):
    """
    :type nums: List[int]
    :type target: int
    :rtype: List[int]
    """
    memo = {}
    for i in range(len(nums)):
        compliment = memo.get(nums[i])
        if compliment != None:
            return [compliment, i]
        memo[target-nums[i]] = i

Javascript