给定一个整数数组nums和一个目标值target，请你在该数组中找出和为目标值的那两个整数，并返回他们的数组下标。
你可以假设每种输入只会对应一个答案。但是，你不能重复利用这个数组中同样的元素。
示例:
给定 nums = [2, 7, 11, 15], target = 9
因为 nums[0] + nums[1] = 2 + 7 = 9
所以返回 [0, 1]
python3
class Solution:
def twoSum(self,nums,target):
sort_nums = sorted(nums)
head = 0
tail = len(nums)-1
sum_result = sort_nums[head] + sort_nums[tail]
while sum_result != target:
if sum_result > target:
tail -= 1
if sum_result < target:
head += 1
sum_result = sort_nums[head] + sort_nums[tail]
m = nums.index(sort_nums[head])
n = nums.index(sort_nums[tail])
if m == n:
nums.remove(nums[m])
n = nums.index(sort_nums[tail]) + 1
result = [m, n]
return result
后来看了大神的解答，发现可以用字典来解答，引用
class Solution:
def twoSum(self, nums, target):
hashmap = {}
for index, num in enumerate(nums):
another_num = target - num
if another_num in hashmap:
return [hashmap[another_num], index]
hashmap[num] = index
return None
