LeetCode练习

练习1

【题目】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, and you may not use the same element twice. Example: Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1].

【答案】

class Solution(object):
    def twoSum(self, nums, target):
        if len(nums) <= 1:
            return False
        buff_dict = {}
        for i in range(len(nums)):
            if nums[i] in buff_dict:
                return [buff_dict[nums[i]], i]
            else:
                buff_dict[target - nums[i]] = i

【评论】利用构建dict来降低复杂度（因为dict的复杂度为O(1))，空间换取时间，而且写得很机智啊，只要循环一遍就可以了

svn://cl@120.26.37.124/server/trunk/rexian_server