Q6: Two Sum. - DSA Patterns (Multi-Lang)

In Simple Words: Iterate through numbers and check if target - current already exists in a Hash Map. If yes, return their indices; otherwise store current -> index.

Time: $O(N)$ | Space: $O(N)$

Multi-Language SolutionsPython 3 • JavaScript • TypeScript • Java • C++

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def twoSum(nums: list[int], target: int) -> list[int]:
    prev_map = {}  # val -> index
    for i, n in enumerate(nums):
        diff = target - n
        if diff in prev_map:
            return [prev_map[diff], i]
        prev_map[n] = i
    return []