Construct a special tree from given preorder traversal

PROBLEM :

Given an array ‘pre[]’ that represents Preorder traversal of a spacial binary tree where every node has either 0 or 2 children. One more array ‘preLN[]’ is given which has only two possible values ‘L’ and ‘N’. The value ‘L’ in ‘preLN[]’ indicates that the corresponding node in Binary Tree is a leaf node and value ‘N’ indicates that the corresponding node is non-leaf node. Write a function to construct the tree from the given two arrays.


Example:

Input:  pre[] = {10, 30, 20, 5, 15},  preLN[] = {'N', 'N', 'L', 'L', 'L'}
Output: Root of following tree
          10
         /  \
        30   15
       /  \
      20   5

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SIMPLE c++ IMPLEMENTATION :
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/*
typedef struct BST
{
int info ;
struct BST *left ;
struct BST *right ;
}tree ;---------------------------------------------*/

tree * create_special_btree(int a[],char b[],int *start,int end)


tree * Special_Btree()
{
int no ;
cout<<"\n how many elements to be entred in the array " ;
cin>>no ;

int i,a[no] ;
char s[no] ;

cout<<"\n enter the array elements " ;
for(i=0;i<no;i++)
cin>>a[i] ;

cout<<"\n enter the status node array " ;
for(i=0;i<no;i++)
cin>>s[i] ;

int start=0 ;

return create_special_btree(a,s,&start,no-1) ;

}

tree * create_special_btree(int a[],char b[],int *start,int end)
{
if((*start)>end)
return NULL ;

tree *temp ;
temp=(tree*)malloc(sizeof(tree)) ;

if((b[(*start)]=='L')||(b[(*start)]=='l'))
{
temp->info=a[(*start)] ;
temp->left=NULL ;
temp->right=NULL ;
(*start)++ ;
}
else
{
temp->info=a[(*start)] ;
(*start)++ ;
temp->left=create_special_btree(a,b,&(*start),end) ;
temp->right=create_special_btree(a,b,&(*start),end) ;
}
return temp ;
}

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