leetcode 1. Two Sum

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].

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

另外就是sort后的解法：

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class Solution:     def twoSum(self, nums, target):         """         :type nums: List[int]         :type target: int         :rtype: List[int]         """                nums2 = [(i,n) for i,n in enumerate(nums)]         nums2.sort(key=lambda x: x[1])         i,j = 0, len(nums2)-1         while i<j:             if nums2[i][1] + nums2[j][1] == target:                 return [nums2[i][0], nums2[j][0]]             elif nums2[i][1] + nums2[j][1] > target:                 j -= 1             else:                 i += 1

 如果是二分查找的two sum，我就不写了。