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001-Two Sum.py
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001-Two Sum.py
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'''
给定一个整数数组和一个目标值,找出数组中和为目标值的两个数。
你可以假设每个输入只对应一种答案,且同样的元素不能被重复利用。
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]
'''
#by myself
class Solution(object):
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
for i,k in enumerate(nums):
for j,l in enumerate(nums):
if i!=j:
if k+l == target:
return [i,j]
#others
class Solution(object):
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
look_up = {}
for i, num in enumerate(nums):
if target-num in look_up:
return [look_up[target-num], i]
look_up[num] = i
return []
# priority
class Solution:
def twoSum(self, nums, target):
mirrors = {}
for idx,num in enumerate(nums):
if num in mirrors:
return [mirrors[num],idx]
mirrors[target - num] = idx