Python Program for Binary Search

This post shows how to implement Binary Search in Python — an efficient algorithm for finding a value in a sorted list, and one of the most frequently asked interview algorithms.

Binary search in Python:

Explanation:
Binary search repeatedly checks the middle element of the list. If the target is smaller, it searches the left half; if larger, the right half. This halves the search space each step, making it far faster than checking every element one by one.

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Python Program for Binary Search

def binary_search(arr, target):
    low, high = 0, len(arr) - 1

    while low <= high:
        mid = (low + high) // 2
        if arr[mid] == target:
            return mid
        elif arr[mid] < target:
            low = mid + 1
        else:
            high = mid - 1
    return -1

numbers = [11, 12, 22, 25, 34, 64, 90]
target = 25

result = binary_search(numbers, target)
if result != -1:
    print(f"Element found at index {result}")
else:
    print("Element not found")

Output:

Element found at index 3

Binary search shows up constantly in interviews — practice more problems like this with our Problem of the Day.

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