contruct full binary tree from preorder and postorder traversals

int search(int post[],int x, int start, int end){
    int index=-1;
    for(int i=start;i<end;i++){
        if(post[i]==x){
            return i;
        }
    }
    return index;
}
Node* buildTree(int pre[], int post[], int preS, int preE,int posS, int posE){
    if(preS>preE){
        return NULL;
    }

    if(preS==preE){
        return pre[preS];
    }
    int index=search(post,posS,posE,pre[preS]);
    int preLS=preS+1;
    int preLE=postLE-postLS+preLS;
    int preRS=preLE+1;
    int preRE=preE;
    int postLS=posS;
    int postLE=index;
    int postRS=index+1;
    int postRE=posE-1;
    Node *root=new newNode(pre[preS]);
    root->left=buildTree(pre,post,preLS,preLE,postLS,postLE);
    root->right=buildTree(pre,post,preRS,preRE,postRS,postRE);
    return root;
}