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62 lines
1.5 KiB
Python
62 lines
1.5 KiB
Python
"""
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Given a sorted array of integers, return indices of the two numbers such
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that they add up to a specific target using the two pointers technique.
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You may assume that each input would have exactly one solution, and you
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may not use the same element twice.
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This is an alternative solution of the two-sum problem, which uses a
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map to solve the problem. Hence can not solve the issue if there is a
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constraint not use the same index twice. [1]
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Example:
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Given nums = [2, 7, 11, 15], target = 9,
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Because nums[0] + nums[1] = 2 + 7 = 9,
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return [0, 1].
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[1]: https://github.com/TheAlgorithms/Python/blob/master/other/two_sum.py
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"""
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from __future__ import annotations
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def two_pointer(nums: list[int], target: int) -> list[int]:
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"""
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>>> two_pointer([2, 7, 11, 15], 9)
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[0, 1]
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>>> two_pointer([2, 7, 11, 15], 17)
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[0, 3]
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>>> two_pointer([2, 7, 11, 15], 18)
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[1, 2]
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>>> two_pointer([2, 7, 11, 15], 26)
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[2, 3]
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>>> two_pointer([1, 3, 3], 6)
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[1, 2]
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>>> two_pointer([2, 7, 11, 15], 8)
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[]
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>>> two_pointer([3 * i for i in range(10)], 19)
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[]
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>>> two_pointer([1, 2, 3], 6)
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[]
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"""
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i = 0
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j = len(nums) - 1
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while i < j:
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if nums[i] + nums[j] == target:
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return [i, j]
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elif nums[i] + nums[j] < target:
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i = i + 1
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else:
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j = j - 1
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return []
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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print(f"{two_pointer([2, 7, 11, 15], 9) = }")
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