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  1. Prepare
  2. C
  3. Functions
  4. Permutations of Strings
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Permutations of Strings

  • a2hnaak
     + 1 comment

    Refer here : https://en.wikipedia.org/wiki/Permutation#Generation_in_lexicographic_order

    int next_permutation(int n, char **s)
{
    int k=-1;
    for(int i=0;i<n-1;i++)
    {
        if(strcmp(s[i],s[i+1])<0)
            k=i;
    }
    // printf("k = %d",k);

    if (k==-1)
    return 0;
    
    int l=-1;
    for(int i=k+1;i<n;i++)
    {
        if(strcmp(s[k],s[i])<0)
            l=i;
    }
    // printf("\nl = %d",l);
    
    
    if(l!=-1)
    {
        char* temp = s[k];
        s[k] = s[l];
        s[l] = temp;
    }
        
    //Reverse the sequence from a[k + 1] up to and including the final element a[n].
    int start=k+1;
    int end=n-1;
    while (start < end) {
      char*  temp = s[start];
        s[start] = s[end];
        s[end] = temp;
        start++;
        end--;
    }
    
        
    
    
    return 1;
}