Write a function that given an expression tree with the following properties:

• leaves are represented with * and internal node with +.
• each node has either 0 or 2 children.

Given the preorder traversal of a tree, construct the tree.

Example: for the following preorder ++*+*** , the tree should look like:

Btree buildFromPreorder_h(char A[], int *counter)
{
    Btree node;
    if(A)
    {
        node=(Btree)malloc(sizeof(struct node));
        node->data=A[*counter];
        node->left=node->right=NULL;
        if(A[*counter]=='*')
            return node;
        (*counter)++;
        node->left = buildFromPreorder_h(A,counter);
        (*counter)++;
        node->right = buildFromPreorder_h(A,counter);
        return node;
    }
    return NULL;
}

Btree buildFromPreorder(char A[])
{
    int counter = 0;
    return buildFromPreorder_h(A, &counter);
}