Python Bisect: Find the index position of the largest value smaller than a given number in a sorted list using Binary Search

Last update on April 23 2025 12:49:04 (UTC/GMT +8 hours)

5. Largest Smaller Value Index

Write a Python program to find the index position of the largest value smaller than a given number in a sorted list using Binary Search (bisect).

Sample Solution:

Python Code:

from bisect import bisect_left  
def Binary_Search(l, x): 
    i = bisect_left(l, x) 
    if i: 
        return (i-1) 
    else: 
        return -1  
nums = [1, 2, 3, 4, 8, 8, 10, 12] 
x = 5 
num_position  = Binary_Search(nums, x) 
if num_position  == -1: 
    print("Not found..!") 
else: 
    print("Largest value smaller than ", x, " is at index ", num_position )

Sample Output:

Largest value smaller than  5  is at index  3

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to find the index of the largest number smaller than a given target in a sorted list using bisect_left.
• Write a Python script to implement a function that returns the index of the element immediately preceding where a target would be inserted in a sorted list.
• Write a Python program to use binary search techniques to determine the index of the greatest element less than a specified value and print that index.
• Write a Python function that finds and returns the index of the largest value that is smaller than the target in a sorted list, including edge case handling when no such element exists.

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