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twosum.py
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twosum.py
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class Solution(object):
def twoSum(self, nums, target):
"""
:type nums: List[int]
:type target: int
:rtype: List[int]
"""
# begin coding
# start by brute force, two for loops
'''
numInts = len(nums)
for i in range(numInts):
for j in range(i+1, numInts):
if nums[j] == target - nums[i]:
return [i, j]
else:
continue
'''
# now try using a hash table
numDict = {}
# first put everything into the hash table, in this case a python dictionary
for i in range(len(nums)):
numDict[i] = nums[i]
# loop thru and check if complement exists in dict, if yes, then equals sum, if no then idk
for i in range(len(nums)):
complement = target - nums[i]
# check to see if complement is in the dictionary, and not the same as the number we're at
if complement in numDict and complement != nums[i]:
# we need to do a reverse lookup so reverse the map
revDict = {v: k for k, v in numDict.items()}
return [i, revDict.get(complement)]