How to Print All Permutations of a Given String in C, C++, JavaScript, and Python.

A permutation is a specific order in which objects can be arranged. For a string of length n, there are n! (n factorial) possible permutations.

This article will guide you through finding all permutations of string using four popular programming languages: C++, Python, JavaScript, and C.

How do permutations work? Let's consider a string, "MUO," and the task of finding its permutations:

Example 1: Let's take the string str = "MUO" The permutations of "MUO" are:

Example 2: Now, let's consider the string str = "AB" The permutations of "AB" are:

Now that you have a basic understanding of permutations, let's explore how you can find them using your preferred programming language.

Please keep in mind that the code examples provided below are tailored to output permutations for three example strings: "MUO," "AB," and "XYZ." If you wish to use any of this code, feel free to copy it and modify the strings to suit your specific project requirements.

Here are the code examples for each programming language:

Below is the C++ program to print all permutations of a string:

// C++ program to print all
 // permutations of a string
 #include <bits/stdc++.h>
 using namespace std;
 
 // Function to print permutations of string
 void findPermutations(string str, int leftIndex, int rightIndex)
 {
  if (leftIndex == rightIndex)
  {
  cout << str << endl;
  }
  else
  {
  for (int i = leftIndex; i <= rightIndex; i++)
  {
  swap(str[leftIndex], str[i]);
  findPermutations(str, leftIndex+1, rightIndex);
  //backtrack
  swap(str[leftIndex], str[i]);
  }
  }
 }
 // Driver Code
 int main()
 {
  string str1 = "MUO";
  int size1 = str1.size();
  cout << "str1: " << str1 << endl;
  cout << "Permutations of " << str1 << ":" << endl;
  findPermutations(str1, 0, size1-1);
  string str2 = "AB";
  int size2 = str2.size();
  cout << "str2: " << str2 << endl;
  cout << "Permutations of " << str2 << ":" << endl;
  findPermutations(str2, 0, size2-1);
  string str3 = "XYZ";
  int size3 = str3.size();
  cout << "str3: " << str3 << endl;
  cout << "Permutations of " << str3 << ":" << endl;
  findPermutations(str3, 0, size3-1);
  return 0;
 }

Output:

str1: MUO
 Permutations of MUO:
 MUO
 MOU
 UMO
 UOM
 OUM
 OMU
 str2: AB
 Permutations of AB:
 AB
 BA
 str3: XYZ
 Permutations of XYZ:
 XYZ
 XZY
 YXZ
 YZX
 ZYX
 ZXY

Next, is the Python code to print all permutations of a string:

# Python program to print all
 # permutations of a string
 def convertToString(List):
  return ''.join(List)
 # Function to print permutations of string
 def findPermutations(s, leftIndex, rightIndex):
  if leftIndex == rightIndex:
  print(convertToString(s))
  else:
  for i in range(leftIndex, rightIndex+1):
  s[leftIndex], s[i] = s[i], s[leftIndex]
  findPermutations(s, leftIndex+1, rightIndex)
  # backtrack
  s[leftIndex], s[i] = s[i], s[leftIndex]
 # Driver Code
 str1 = "MUO"
 size1 = len(str1)
 s1 = list(str1)
 print("str1:", str1)
 print("Permutations of", str1,":")
 findPermutations(s1, 0, size1-1)
 str2 = "AB"
 size2 = len(str2)
 s2 = list(str2)
 print("str2:", str2)
 print("Permutations of", str2,":")
 findPermutations(s2, 0, size2-1)
 str3 = "XYZ"
 size3 = len(str3)
 s3 = list(str3)
 print("str3:", str3)
 print("Permutations of", str3,":")
 findPermutations(s3, 0, size3-1)

Output:

str1: MUO
 Permutations of MUO:
 MUO
 MOU
 UMO
 UOM
 OUM
 OMU
 str2: AB
 Permutations of AB:
 AB
 BA
 str3: XYZ
 Permutations of XYZ:
 XYZ
 XZY
 YXZ
 YZX
 ZYX
 ZXY

Here's how you print permutations in JavaScript:

// JavaScript program to print all
 // permutations of a string
 // Function to swap characters of the string
 function swap(str, leftIndex, i) {
  let temp;
  let tempArray = str.split("");
  temp = tempArray[leftIndex] ;
  tempArray[leftIndex] = tempArray[i];
  tempArray[i] = temp;
  return (tempArray).join("");
 }
 // Function to print permutations of string
 function findPermutations(str, leftIndex, rightIndex) {
  if (leftIndex == rightIndex) {
  document.write(str + "<br>");
  } else {
  for (let i = leftIndex; i <= rightIndex; i++) {
  str = swap(str, leftIndex, i);
  findPermutations(str, leftIndex+1, rightIndex);
  //backtrack
  str = swap(str, leftIndex, i);;
  }
  }
 }
 // Driver Code
 var str1 = "MUO";
 var size1 = str1.length;
 document.write("str1: " + str1 + "<br>");
 document.write("Permutations of " + str1 + ":" + "<br>");
 findPermutations(str1, 0, size1-1);
 var str2 = "AB";
 var size2 = str2.length;
 document.write("str2: " + str2 + "<br>");
 document.write("Permutations of " + str2 + ":" + "<br>");
 findPermutations(str2, 0, size2-1);
 var str3 = "XYZ";
 var size3 = str3.length;
 document.write("str3: " + str3 + "<br>");
 document.write("Permutations of " + str3 + ":" + "<br>");
 findPermutations(str3, 0, size3-1);

Output:

str1: MUO
 Permutations of MUO:
 MUO
 MOU
 UMO
 UOM
 OUM
 OMU
 str2: AB
 Permutations of AB:
 AB
 BA
 str3: XYZ
 Permutations of XYZ:
 XYZ
 XZY
 YXZ
 YZX
 ZYX
 ZXY

Below is a C program that prints all permutations of a string:

// C program to print all
 // permutations of a string
 #include <stdio.h>
 #include <string.h>
 // Function to swap characters of the string
 void swap(char str[], int leftIndex, int i)
 {
  char temp = str[leftIndex];
  str[leftIndex] = str[i];
  str[i] = temp;
 }
 // Function to print permutations of string
 void findPermutations(char str[], int leftIndex, int rightIndex)
 {
  if (leftIndex == rightIndex)
  {
  printf("%s \⁠n", str);
  }
  else
  {
  for (int i = leftIndex; i <= rightIndex; i++)
  {
  swap(str, leftIndex, i);
  findPermutations(str, leftIndex+1, rightIndex);
  //backtrack
  swap(str, leftIndex, i);
  }
  }
 }
 // Driver Code
 int main()
 {
  char str1[] = "MUO";
  int size1 = strlen(str1);
  printf("str1: %s \⁠n", str1);
  printf("Permutations of %s: \⁠n", str1);
  findPermutations(str1, 0, size1-1);
  char str2[] = "AB";
  int size2 = strlen(str2);
  printf("str2: %s \⁠n", str2);
  printf("Permutations of %s: \⁠n", str2);
  findPermutations(str2, 0, size2-1);
  char str3[] = "XYZ";
  int size3 = strlen(str3);
  printf("str3: %s \⁠n", str3);
  printf("Permutations of %s: \⁠n", str3);
  findPermutations(str3, 0, size3-1);
  return 0;
 }

Output:

str1: MUO
 Permutations of MUO:
 MUO
 MOU
 UMO
 UOM
 OUM
 OMU
 str2: AB
 Permutations of AB:
 AB
 BA
 str3: XYZ
 Permutations of XYZ:
 XYZ
 XZY
 YXZ
 YZX
 ZYX
 ZXY

In this article, we will explore the process of generating all permutations of a given string using various programming languages. Although the presented sample programs may not be the only solutions to tackle permutations, they serve as excellent starting points for beginners who are unfamiliar with implementing this concept in their code.

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