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].

Solutions - Python:

#!/usr/bin/env python
# -*- coding = utf-8 -*-

""" @ Create Time: 2017/12/24 @ Author: songpo.zhang @ Target: 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 Given nums = [2, 7, 11, 15], target = 9, Because nums[0] + nums[1] = 2 + 7 = 9, return [0, 1]. """
def twoSum(nums, target):
    result = {}
    for i, num in enumerate(nums):
        if target - num in result:
            return [result[target - num], i]
        result[num] = i
        # print(result)

nums = [2, 7, 11, 15]
target = 9
print(twoSum(nums, target))