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Two SumEasy1/3
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Problem
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1. Two SumEasy
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+12
Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.
You may assume each input has exactly one solution, and you may not use the same element twice.
Examples
Example 1
Input: nums = [2,7,11,15], target = 9
Output: [0,1]
Because nums[0] + nums[1] == 9
Example 2
Input: nums = [3,2,4], target = 6
Output: [1,2]
Constraints
2 <= nums.length <= 10⁴
-10⁹ <= nums[i] <= 10⁹
Only one valid answer exists.
Expected Complexity
TimeO(n)
SpaceO(n)

Python 3▾

+12

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def two_sum(nums, target):
    # Use a hash map for O(1) lookups
    seen = {}

    for i, num in enumerate(nums):
        complement = target - num

        if complement in seen:
            return [seen[complement], i]

        seen[num] = i

    return []

Test CasesConsole3/3 Passed

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