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0001_Two_Sum.py
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0001_Two_Sum.py
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'''
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:
Input: nums = [2, 7, 11, 15], target = 9
Output: return [0, 1]
Explanation nums[0] + nums[1] = 2 + 7 = 9
'''
from typing import List
class Solution:
''' Approach #1 (Using Hash Table)'''
def twoSum(self, nums: List[int], target: int) -> List[int]:
# Dictionary to store nums and their index
# Dictionary key stores the number and its value store the index for the respective number
Hash = dict()
for idx in range(0,len(nums)):
counterPart = target-nums[idx]
# Check if target-currentnumber (counter part) is present in Hash
# In case of above example 9-2=7 (7 will be present in the Hash) so index of 2 and 7 are the result
if((counterPart in Hash) and idx!=Hash[counterPart]):
return [Hash[counterPart],idx]
# Update the Hash for current index
Hash[nums[idx]] = idx
if __name__ == '__main__':
sol = Solution()
nums = [2, 7, 11, 15]; target = 9
print(sol.twoSum(nums,target))