Binary Search
easy⏱ 15 mintypescriptchallengesproblem-solving-basic-
LEARN BY DOINGPut your intuition to work3 steps
Binary Search
Use the lesson’s examples and explanation to check your idea.
Personal reflection. Nothing is sent to an AI service.GUIDED PRACTICE · 5–10 MINExplain how each comparison narrows a sorted search interval.
Before you start: Array indices and comparisons
Pseudocode: trace the idea, then apply it in the lesson’s language.
values = [2, 5, 8, 12, 16]
target = 12
low = 0
high = 4
mid = floor((low + high) / 2)
Walk through the example
Guided trace, not live execution
low=0 · mid=2 · high=4 → value=8low=3 · mid=3 · high=4 → value=12
8 < 12: discard indices 0–2.
Sample case — your program reads stdin and prints to stdout.
Starter Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return -1.
Binary search works by repeatedly dividing the search interval in half.
Example: nums=[−1,0,3,5,9,12], target=9 → index 4
Input format
Line 1: n (array size). Line 2: n space-separated sorted integers. Line 3: target.
Output format
The index of target (0-based), or -1 if not found.
Constraints
1 ≤ n ≤ 10⁴, -10⁴ ≤ nums[i], target ≤ 10⁴