两数之和

class Solution(object):

def twoSum(self, nums, target):
    """
    :type nums: List[int]
    :type target: int
    :rtype: List[int]
    >>> Solution().twoSum([2, 7, 11, 15], 9)
    [0, 1]
    """
    complement_map = {}
    for index, x in enumerate(nums):
        if complement_map.get(x, None) is None:
            complement_map[target - x] = index
        else:
            return [complement_map.get(x), index]