C++ Program to Permute All Letters of an Input String

This C++ Program Permutes All Letters Of An Input String.

It iterates from the 0th letter to last letter in a string, swaps values and recursively call permute function to print values.

The program has an input as a string. This prints permutation of all letters of an input string.

Here is source code of the C++ Program to Find Permute All Letters of an Input String. The C++ program is successfully compiled and run on g++-4.3.2 on a Linux system. The program output is also shown below.

//This is a C++ Program to Permute All Letters Of An Input String.

```
#include <iostream>
```
```
#include <string>
```
```
#include <algorithm>
```
```
 
```
```
using namespace std;
```

void permute (string temp_str, int start, int end)

```
{
```
```
  int i;
```
```
  if (start == end){
```
```
    cout << temp_str << " ";
```
```
  }
```
```
  else{
```

    for (int i = start; i < temp_str.length (); ++i){

      swap (temp_str[start], temp_str[i]);

      permute (temp_str, start + 1, end);

      swap (temp_str[start], temp_str[i]);

```
    }
```
```
  }
```
```
}
```
```
int main()
```
```
{
```
```
  string input_str;
```
```
  bool flag = false;
```
```
  cout << "Enter String : ";
```
```
  cin >> input_str;
```

  for (int i = 0; i < input_str.length () - 1; ++i)

```
  {
```

    if (input_str[i] == input_str[i + 1])

```
    {
```
```
    flag = true;
```
```
    break;
```
```
    }
```
```
    else {
```
```
      flag = false;
```
```
      break;
```
```
    }
```
```
  }
```
```
  if (flag)
```
```
  {
```

    cout << "The permutation of " << input_str << " is : " << input_str << endl;

```
  }
```
```
  else 
```
```
  {
```

    cout << "The permutations of " << input_str << " are : " << endl;

    permute (input_str, 0, input_str.length () - 1);

```
  }
```
```
  cout << endl;
```
```
  return 0;
```
```
}
```

Output :

 
$ g++ PermuteString.cpp
$ ./a.out
 
Enter String : bac
The permutations of bac are : bac bca abc acb cab cba 
Enter String : aaaa
The permutation of aaaaa is : aaaaa
 
Enter String : b
The permutations of b are : b

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