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].

注意点：

• 返回的坐标一要比坐标二小

解题思路

第一遍遍历整个数组，用字典hash_map记录数值和它的坐标，第二遍遍历数组，判断（目标数字-当前数字）是否在hash_map中，如果在，且它的下标与当前数字的下标不相同，则说明存在这两个数，返回坐标。

# -*- coding: utf-8 -*-
'''enumerate函数用于遍历序列中的元素以及它们的下标,多用于在for循环中得到计数,enumerate参数为可遍历的变量，如 字符串，列表等
'''
__author__ = 'tongbao'
class Solution(object):
    def twoSum(self,nums,target):
        hash_map = {}
        for id,value in enumerate(nums):
            hash_map[value] = id
        for id1,value in enumerate(nums):
            if target - value in hash_map:
                id2 = hash_map[target-value]
                if id1 != id2:
                    return [id1,id2]