Write a program to print all permutations of a given string

Write a program to print all permutations of a given string

A permutation, also called an “arrangement number” or “order,” is a rearrangement of the elements of an ordered list S into a one-to-one correspondence with S itself. A string of length n has n! permutation.
Source: Mathword(http://mathworld.wolfram.com/Permutation.html)

Below are the permutations of string ABC.
ABC, ACB, BAC, BCA, CAB, CBA

Here is a solution using backtracking.

• C/C++
• Python

# Python program to print all permutations with
# duplicates allowed

# Function to swap values
def swap(a,l,r):
    t = a[l]
    a[l] = a[r]
    a[r] = t
    return a

def toList(string):
    List = []
    for x in string:
        List.append(x)
    return List

def toString(List):
    return ''.join(List)

# Function to print permutations of string
# This function takes three parameters:
# 1. String
# 2. Starting index of the string
# 3. Ending index of the string.
def permute(a, l, r):
    if l==r:
        print toString(a)
    else:
        for i in xrange(l,r+1):
            a = swap(a,l,i)
            permute(a, l+1, r)
            a = swap(a,l,i) # backtrack

# Driver program to test the above function
string = "ABC"
n = len(string)
a = toList(string)
permute(a, 0, n-1)

# This code is contributed by Bhavya Jain

Output:

ABC
ACB
BAC
BCA
CBA
CAB

Algorithm Paradigm: Backtracking
Time Complexity:  O(n*n!)

Please write comments if you find the above codes/algorithms incorrect, or find other ways to solve the same problem.