Two 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:

Given nums = [2, 7, 11, 15], target = 9,
Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

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

class Solution:
    # @param {integer[]} nums
    # @param {integer} target
    # @return {integer[]}
    def twoSum(self, nums, target):
        got = {}
        for n in range(len(nums)):
            if nums[n] not in got:
                got[target - nums[n]] = n + 1
            else:
                return got[nums[n]], n + 1
        return -1, -1

Easier:

class Solution(object):
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        got = {}
        for i, n in enumerate(nums):
            if n in got:
                return got[n], i
            else:
                got[target - n] = i