Implement binary search
See this course’s project requirements
A tested Python catalog search with linear and binary methods, comparison counts, sortedness checks and a justified method choice.
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What to include
- A three-case lookup contract with results 5,-1,-1.
- A linear-search trace with six and seven comparisons.
- A sortedness rule and two-step interval trace.
- A terminating binary-search implementation and boundary trace.
- A cost comparison distinguishing lookup from total work.
- A checked algorithm-comparison packet with honest measurement limits.
Review and revise
Use these criteria to check your work and choose what to improve.
- The implementation or declared simulation follows the supplied contract and retains inspectable original inputs.
- Normal, boundary and rejected cases are recorded with expected versus observed results.
- The changed case has a correct explanation and does not rely on hidden state.
- The project includes source, outputs, instructions and honest tool, privacy and verification limits.
Want more background?
The idea in everyday life
Read the supplied binary implementation. It uses integer middle=(low+high)//2 and returns -1 after the loop.
An inclusive interval is empty when low>high. Updating beyond the tested middle guarantees progress; retaining the same middle can produce an infinite loop.
Implement binary search — original worked practice
An inclusive interval is empty when low>high. Updating beyond the tested middle guarantees progress; retaining the same middle can produce an infinite loop.
Read the supplied binary implementation. It uses integer middle=(low+high)//2 and returns -1 after the loop.
1. Step 1
Run or trace target 52.
You should see: The function returns index 5.
This keeps the rule and its observable result together.
2. Step 2
Trace missing 30: middle 31, then 18, then 25.
You should see: After 25 is too small, low 3 exceeds high 2.
This keeps the rule and its observable result together.
3. Step 3
Check a one-value catalog [8] with targets 8 and 9.
You should see: The results are 0 and -1.
This keeps the rule and its observable result together.
4. Step 4
Record why middle+1 and middle-1 are required.
You should see: A terminating binary-search implementation and boundary trace.
This keeps the rule and its observable result together.
What to finish
A terminating binary-search implementation and boundary trace.
Watch for this
Counting only midpoint probes while omitting the implemented sorted-input validation pass.
How can I tell I understand it?
Explain and demonstrate the required distinction: An inclusive interval is empty when low>high. Updating beyond the tested middle guarantees progress; retaining the same middle can produce an infinite loop. Show a changed input and the expected result without weakening this contract.
Quick knowledge check
Answer all 3 questions. Get at least 2 right and the lesson completes automatically.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.
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Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
Source & access notes · checked 2026-10-01
Relevant documented module/API behavior inspected during expansion authoring; actual execution evidence is recorded separately. No grant eligibility is established.
Access: Official page retrieved with the web reader on 2026-10-01. Documentation reading does not certify execution in every native tool or browser.
Reuse: Original local practice files, fictional data, worked examples and questions. Concepts paraphrased and linked; source exercises are not copied.
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