Python Program for Binary Search( Iterative method)

 

In  this search algorithm takes advantage of a collection of elements that is already sorted by ignoring half of the elements after just one comparison. 

1. Compare x with the middle element.
2. If x matches with the middle element, we return the mid index.
3. Else if x is greater than the mid element, then x can only lie in the right (greater) half subarray after the mid element. Then we apply the algorithm again for the right half.
4. Else if x is smaller, the target x must lie in the left (lower) half. So we apply the algorithm for the left half.

# Iterative Binary Search Function

# It returns index of x in given array arr if present,

# else returns -1

def binary_search(arr, x):

    low = 0

    high = len(arr) - 1

    mid = 0

 

    while low <= high:

 

        mid = (high + low) // 2

 

        # If x is greater, ignore left half

        if arr[mid] < x:

            low = mid + 1

 

        # If x is smaller, ignore right half

        elif arr[mid] > x:

            high = mid - 1

 

        # means x is present at mid

        else:

            return mid

 

    # If we reach here, then the element was not present

    return -1

 

 

# Test array

arr = [ 2, 3, 4, 10, 40 ]

x = 10

 

# Function call

result = binary_search(arr, x)

 

if result != -1:

    print("Element is present at index", str(result))

else:

    print("Element is not present in array")

To print the number of occurrences of a given alphabet in a given string.

 Write a Python Program to Count Occurrence of a Character in a String with a practical example. This python program allows you to enter a string and a character.

# Python Program to Count Occurrence of a Character in a String

string = input("Please enter your own String : ")
char = input("Please enter your own Character : ")

count = 0
for i in range(len(string)):
    if(string[i] == char):
        count = count + 1

print("The total Number of Times ", char, " has Occurred = " , count)

To print the words starting with a particular alphabet in a user entered string.

 

Python program:

1 2 3 4 5 6 7 8 9 10 11

s = input("Enter any sentences : ") a = input("Enter any alphabet to find :") found = False words = s.split() for word in words:     if word.startswith(a):         print(word)         found = True     if (found == False):         print("No word starting with user entered alphabet")

Output

Enter any sentences : hello athang whats up
Enter any alphabet to find :h
hello

Enter any sentences : today is holiday ,we can take rest today
Enter any alphabet to find :t
today
take
today

To count the number of vowels in a user entered string.

 Program/Source Code

Here is source code of the Python Program to remove the nth index character from a non-empty string. The program output is also shown below.

string=raw_input("Enter string:")
vowels=0
for i in string:
      if(i=='a' or i=='e' or i=='i' or i=='o' or i=='u' or i=='A' or i=='E' or i=='I' or i=='O' or i=='U'):
            vowels=vowels+1
print("Number of vowels are:")
print(vowels)

Runtime Test Cases

 
Case 1:
Enter string:Hello world
Number of vowels are:
3
 
Case 2:
Enter string:WELCOME
Number of vowels are:
3

To print the first ‘n’ multiples of a given number.

 

Python program to print multiples of a given number

The program to find the multiple sof a number in python is as follows:

 

# Owner : TutorialsInhand Author : Devjeet Roy

number = int(input("Enter number: "))

print("The multiples are: ")
for i in range(1,11):
    print(number*i, end =" ")

The output of the program to print multiples of a given number in python is as follows:

 

PS C:\Users\DEVJEET\Desktop\tutorialsInHand> python code.py
Enter number: 5
The multiples are:
5 10 15 20 25 30 35 40 45 50