ConstructBinaryTreeFromInorderAndPostOrderTraversal`

/************************************************************
   
   Following is the TreeNode class structure
   
   class TreeNode<T>
   { 
   public:
        T data; 
        TreeNode<T> *left;
        TreeNode<T> *right;
   
        TreeNode(T data) 
  		{ 
            this -> data = data; 
            left = NULL; 
            right = NULL; 
        }
   };
   
   
 ************************************************************/

TreeNode<int> * helper(vector<int> & in,int ins,int ine,vector<int> & po,int pos,int poe)
{
    if(ins>ine)
        return NULL;
        int rootdata=po[poe];
        TreeNode<int> * root=new TreeNode<int>(rootdata);
        int rootindex;
        for(int i=ins;i<=ine;i++)
        {
            if(in[i]==rootdata)
            {
                rootindex=i;
                break;
            }
        }
        int rpoe=poe-1;
        int lpos=pos;
        int line=rootindex-1;
        int lins=ins;
        int rins=rootindex+1;
        int rine=ine;
        int lpoe;
        int rpos;
         rpos=rpoe-(rine-rins);
        lpoe=rpos-1;
        root->left=helper(in,lins,line,po,lpos,lpoe);
        root->right=helper(in,rins,rine,po,rpos,rpoe);
        return root;
        
   
        
}
TreeNode<int>* getTreeFromPostorderAndInorder(vector<int>& postOrder, vector<int>& inOrder) 
{
    int n=inOrder.size();
    int st=0;
    int ed=n-1;
    return helper(inOrder,st,ed,postOrder,st,ed);
}