【leetcode】1.Two Sum 解题报告

给定一个数组和一个target，求出满足数组中满足两个数之和等于target的数的下标

方法一：
第一个想到的肯定是hash表，python里面是字典，遍历一遍即可，放入的同时检查target减去放入的元素是否在hash表中
python

class Solution:
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        dictionary = {}
        for i in range(len(nums)):
            if target-nums[i]  in dictionary:
                return [i,dictionary[target-nums[i]]]
            else :
                dictionary[nums[i]] = i
        return [0,0]

beat 83.92%

如果在遍历的过程中加点修改，省去根据i找nums[i]的过程

class Solution:
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        dictionary = {}
        for i,num in enumerate(nums):
            if target - num in dictionary:
                return [i,dictionary[target-num]]
            dictionary[num] = i
        return [0, 0]

wtf，还是beat 83.92%