tree -> leaf

tree -> (tree tree)

leaf -> integer

using namespace std;

int main()
{
    string str,st;

    int index = 0,k=0,i=0;
    double s=0,res=0;
    res = 0;
    char chr;
    getline(cin,str);

    while (index < str.length())
    {
        chr = str[index];

        if ((chr == '1') || (chr == '2') || (chr == '3') || (chr == '4') || (chr == '5') || (chr == '6') || (chr == '7') || (chr == '8') || (chr == '9') || (chr == '10') )
            {
                st = chr;
                k = atoi(st.c_str()); cout << "k=" << k << endl;
                res = res + k*pow(0.5, s); cout << "s=" << s << endl;
            }

        if (chr == '(')
        {
            s = s+1 ;

        }
        if (chr == ')')
        {
            s = s-1;

        }
        cout << "ravn" << res<<endl;

        index++;
    }
        cout << "ravn" << res;
        system("pause");
}

struct tree
{
    int value;
    tree* left;
    tree* right;
};

/
 / 3
1  2

tree* root = new tree();
// правое поддерево - лист
tree* r = new tree();
r->value = 3;
root->right = r;
// левое поддерево содержит два подподдерева
tree* l = new tree();
tree* ll = new tree();
ll->value = 1;
tree* lr = new tree();
lr->value = 2;
l->left = ll;
l->right = lr;
root->left = l;

int numberofleaves(tree* t)
{
    if (t->left == nullptr && t->right == nullptr) // лист
        return 1;
    else
        return numberofleaves(t->left) + numberofleaves(t->right);
}