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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. void swap(char *x, char *y)
  4. {
  5.     char temp;
  6.     temp = *x;
  7.     *x = *y;
  8.     *y = temp;
  9. }
  10. void permute(char *a, int l, int r)
  11. {
  12. 	static int count=0;
  13. 	count++;
  14. 	cout<<"Function permute() is called   "<<count<<"  time"<<endl;
  15.    int i;
  16.    if (l == r){
  17.        for(int k=0;k<=r;k++)
  18.         cout<<a[k];
  19.        cout<<endl;
  20.    }
  21.    else
  22.    {
  23.        for (i = l; i <= r; i++)
  24.        {
  25. 		   cout<<"Before 1st swap i:"<<i<<"   l:"<<l<<endl;
  26.           swap((a+l), (a+i));
  27.           cout<<"Permute() is being called - "<<endl;
  28.           permute(a, l+1, r);
  29.           cout<<"Before 2nd swap i:"<<i<<"   l:"<<l<<endl;
  30.           swap((a+l), (a+i)); //backtrack
  31.        }
  32.    }
  33. }
  34.  
  35. /* Driver program to test above functions */
  36. int main()
  37. {
  38.     char str[] = "ABC";
  39.     int n = strlen(str);
  40.     permute(str, 0, n-1);
  41.     return 0;
  42. }
  43.  
Success #stdin #stdout 0s 3144KB
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stdin
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Standard input is empty
stdout
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Function permute() is called   1  time
Before 1st swap i:0   l:0
Permute() is being called - 
Function permute() is called   2  time
Before 1st swap i:1   l:1
Permute() is being called - 
Function permute() is called   3  time
ABC
Before 2nd swap i:1   l:1
Before 1st swap i:2   l:1
Permute() is being called - 
Function permute() is called   4  time
ACB
Before 2nd swap i:2   l:1
Before 2nd swap i:0   l:0
Before 1st swap i:1   l:0
Permute() is being called - 
Function permute() is called   5  time
Before 1st swap i:1   l:1
Permute() is being called - 
Function permute() is called   6  time
BAC
Before 2nd swap i:1   l:1
Before 1st swap i:2   l:1
Permute() is being called - 
Function permute() is called   7  time
BCA
Before 2nd swap i:2   l:1
Before 2nd swap i:1   l:0
Before 1st swap i:2   l:0
Permute() is being called - 
Function permute() is called   8  time
Before 1st swap i:1   l:1
Permute() is being called - 
Function permute() is called   9  time
CBA
Before 2nd swap i:1   l:1
Before 1st swap i:2   l:1
Permute() is being called - 
Function permute() is called   10  time
CAB
Before 2nd swap i:2   l:1
Before 2nd swap i:2   l:0
https://ideone.com/aGEmEt
language:
C++ (gcc 8.3)
created:
8 years ago
visibility:
public

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