Binary Search — AI Tutor

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algorithms

Write a function solution(arr, target) that performs binary search on a sorted list arr and returns the index of target, or -1 if not found.

Example

solution([1, 3, 5, 7, 9], 5)  → 2
solution([1, 3, 5, 7, 9], 6)  → -1

solution.py

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📊 Test Results

Run your code to see test results here.

Every challenge runs your code by calling a function. You must define a function named solution(...) that returns the answer.

Key rule: use return — not print(). The grader only checks the returned value; anything you print is ignored.

✗ Won't be graded

def solution(a, b):
    print(a + b)

✓ Correct

def solution(a, b):
    return a + b

What the grader sends

Your function is called with the challenge's test inputs, for example:

solution(3, 5)   # expects 8

Match the parameter names and count shown in the challenge description, and always finish with a return.