【leetcode 1】两数之和

借用字典来减少时间复杂度

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        d = {}
        for i in range(len(nums)):
            find = target - nums[i]
            if d.get(find,None)==None:
                d[nums[i]] = i
            else:
                return [d[find],i]