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Binary Search•Pattern: Binary Search•Medium

Find peak element in unsorted array

Problem Intuition & Objective

Find an index i such that nums[i] > nums[i-1] and nums[i] > nums[i+1].

Time ComplexityO(log n)
Optimal
Space ComplexityO(1)
Memory Bounds
Optimal Algorithmic Approach

Binary search using the slope direction to narrow the search.

Core Invariants & Edge Cases

  • Binary search: if nums[mid] < nums[mid+1], peak is to the right
  • Otherwise peak is at mid or to the left
  • Boundary elements count as neighbors -∞
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