1.py

"""给定一个整数数组 nums 和一个目标值 target，请你在该数组中找出和为目标值的那 两个 整数，并返回他们的数组下标。

你可以假设每种输入只会对应一个答案。但是，你不能重复利用这个数组中同样的元素。

示例:

给定 nums = [2, 7, 11, 15], target = 9

因为 nums[0] + nums[1] = 2 + 7 = 9
所以返回 [0, 1]
"""


class Solution:
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        hashmap = {}
        for index, num in enumerate(nums):
            another_num = target - num
            if another_num in hashmap:
                return [hashmap[another_num], index]
            hashmap[num] = index
        return None


class Solution2:
    def twoSum(self, nums, target):
        """
        :param nums: list[int]
        :param target: int
        :return: list[int]
        """
        hashmap = {}
        for i in range(len(nums)):
            if target - nums[i] in hashmap:
                return [hashmap[target - nums[i]], i]
            else:
                hashmap[nums[i]] = i
        return []


s = Solution2()
print(s.twoSum(nums=[2, 8, 11, 15], target=17))