search_in_rotated_sorted_array.py

from typing import List

class Solution:
    def search(self, nums: List[int], target: int) -> int:
        """
        There is an integer array nums sorted in ascending order (with distinct values).

        Prior to being passed to your function, nums is possibly rotated at an unknown pivot index k (1 <= k < nums.length) such that the resulting array is [nums[k], nums[k+1], ..., nums[n-1], nums[0], nums[1], ..., nums[k-1]] (0-indexed). For example, [0,1,2,4,5,6,7] might be rotated at pivot index 3 and become [4,5,6,7,0,1,2].

        Given the array nums after the possible rotation and an integer target, return the index of target if it is in nums, or -1 if it is not in nums.

        You must write an algorithm with O(log n) runtime complexity.
        """
        left = 0
        right = len(nums) - 1
        while left <= right:
            mid = left + (right - left) // 2
            if nums[mid] == target:
                return mid
            if nums[left] <= nums[mid]:
                if nums[left] <= target <= nums[mid]:
                    right = mid - 1
                else:
                    left = mid + 1
            else:
                if nums[mid] <= target <= nums[right]:
                    left = mid + 1
                else:
                    right = mid - 1
        return -1

# Time complexity: O(log n)
# Space complexity: O(1)

import unittest

class TestSolution(unittest.TestCase):
    def setUp(self) -> None:
        self.solution = Solution()

    def test_search(self):
        self.assertEqual(self.solution.search([4,5,6,7,0,1,2], 0), 4)
        self.assertEqual(self.solution.search([4,5,6,7,0,1,2], 3), -1)
        self.assertEqual(self.solution.search([1], 0), -1)

if __name__ == '__main__':
    unittest.main()