EASY NC#28 Binary Search
704. Binary Search
📖 Problem
Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1. You must write an algorithm with O(log n) runtime complexity.
🧠 Visual Learning Aid
1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases
JS/TS Refreshers
- •Array methods (`push`, `pop`, `shift`, `slice`)
- •Object/Map/Set usage patterns
- •Function parameter and return typing
- •In-place array updates
- •Sorted array traversal
- •Boundary condition checks
Logical Thinking Concepts
- •Define invariants before coding
- •Check edge cases first (`[]`, single element, duplicates)
- •Estimate time/space before implementation
- •Apply Two Pointers reasoning pattern
- •Apply Binary Search reasoning pattern
- •Apply Recursion reasoning pattern
💡 Approach
- → Use two pointers (left and right)
- → Calculate mid and compare with target
- → Narrow search space by half each iteration
- → Time: O(log n), Space: O(1)
🛠️ Hints & Pitfalls
Hints
- •Use two pointers (left and right)
- •Calculate mid and compare with target
- •Narrow search space by half each iteration
Common Pitfalls
- •Time: O(log n), Space: O(1)
🧪 Test Cases
Hidden tests on submit: 5
Test Case 1
Not run Input:
search([-1, 0, 3, 5, 9, 12], 9); Expected:
4 Test Case 2
Not run Input:
search([-1, 0, 3, 5, 9, 12], -1); Expected:
0 Test Case 3
Not run Input:
search([-1, 0, 3, 5, 9, 12], 12); Expected:
5 📝 Code Editor
📤 Output