Python Program to Print All Permutations of a String in Lexicographic Order without Recursion

When it is required to print all the permutations of a string in the lexicographic order without using recursion, a method is defined, that takes the string as the parameter. It uses a simple ‘for’ loop to iterate over the string elements and uses ‘while’ condition to check for certain constraints.

Below is the demonstration of the same −

Example

 Live Demo

from math import factorial def lex_permutation(my_string): for i in range(factorial(len(my_string))):    print(''.join(my_string))    i = len(my_string) - 1    while i > 0 and my_string[i-1] > my_string[i]:       i -= 1    my_string[i:] = reversed(my_string[i:])    if i > 0:       q = i       while my_string[i-1] > my_string[q]:          q += 1       temp_variable = my_string[i-1]       my_string[i-1]= my_string[q]       my_string[q]= temp_variable my_string = 'bhd' print("The string is ") print(my_string) my_string = list(my_string) print("The string is being sorted") my_string.sort() lex_permutation(my_string)

Output

The string is bhd The string is being sorted bdh bhd dbh dhb hbd hdb

Explanation

• The required packages are imported.

• A method named ‘lex_permutation’ is defined that takes the string as a parameter.

• It uses the factorial method and iterates through the factorial of the string.

• The reversed string and the original string are compared.

• A simple swapping is done.

• Outside the method, the string is defined, and is displayed on the console.

• It is then sorted.

• The method is called by passing this string.

• The output is displayed on the console.