Print all permutations of a given string

Printing all permutations of a given string is an example of backtracking problem. We will reduce the size of the substring to solve the sub-problems, then again backtrack to get another permutation from that section.

For an example, if the string is ABC, the all permutations will be ABC, ACB, BAC, BCA, CAB, CBA.

The complexity of this algorithm is O(n!). It is a huge complexity. When the string size increases, it takes a longer time to finish the task.

Input and Output

Input:
A string “ABC”
Output:
All permutations of ABC is:
ABC
ACB
BAC
BCA
CBA
CAB

Algorithm

stringPermutation(str, left, right)

Input: The string and left and right index of characters.

Output: Print all permutations of the string.

Begin
   if left = right, then
      display str
   else
      for i := left to right, do
         swap str[left] and str[i]
         stringPermutation(str, left+1, right)
         swap str[left] and str[i]             //for backtrack
      done
End

Example

#include<iostream>
using namespace std;

void stringPermutation(string str, int left, int right) {
   if(left == right)
      cout << str << endl;
   else {
      for(int i = left; i<= right; i++) {
         swap(str[left], str[i]);
         stringPermutation(str, left + 1, right);
         swap(str[left], str[i]); //swap back for backtracking
      }
   }
}

int main() {
   string str = "ABC";
   cout << "All permutations of " << str << " is: " <<endl<<endl;
   stringPermutation(str, 0, str.size()-1);
}

Output

All permutations of ABC is:
ABC
ACB
BAC
BCA
CBA
CAB

Arjun Thakur

Updated on 17-Jun-2020 09:55:28

• Related Questions & Answers
• Python Program to print all permutations of a given string
• C Program to print all permutations of a given string
• Print all permutations of a string in Java
• Print all distinct permutations of a given string with duplicates in C++
• Print all palindrome permutations of a string in C++
• Print all the palindromic permutations of given string in alphabetic order in C++
• All permutations of a string using iteration?
• How to find all possible permutations of a given string in Python?
• C++ Permutations of a Given String Using STL
• Java Program to print distinct permutations of a string
• Python Program to Print All Permutations of a String in Lexicographic Order without Recursion
• Python Program to Print All Permutations of a String in Lexicographic Order using Recursion
• Print all permutations with repetition of characters in C++
• Program to print all substrings of a given string in C++
• Creating all possible unique permutations of a string in JavaScript