LeetCode 33, Medium. Topics: Array, Binary Search. View on LeetCode.
Generate this problem as a practice environment: tested reference solution, 15 parametrized pytest cases, and a playground notebook:
Problem
There is an integer array nums sorted in ascending order (with distinct values).
Prior to being passed to your function, nums is possibly left rotated at an unknown 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 left rotated by 3 indices 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.
Examples
Constraints
1 <= nums.length <= 5000
-10^4 <= nums[i] <= 10^4
- All values of
nums are unique.
nums is an ascending array that is possibly rotated.
-10^4 <= target <= 10^4
Solution
Reference implementation from solution.py on GitHub, full suite in test_solution.py:
Complexity
Grind 75, Grind, Blind 75, NeetCode 150, NeetCode 250, NeetCode All, AlgoMaster 75. Last modified on September 7, 2026