void MovieTree::leftRotation(TreeNode* curr)
{
    TreeNode*x = curr;
    TreeNode*xp = x->parent;
    TreeNode*y = x->rightChild;
    TreeNode*yl = y->leftChild;
    if(xp)
        xp->leftChild==x ? xp->leftChild=y : xp->rightChild=y;
    y->parent=xp;
    y->leftChild=x;
    x->rightChild=yl;
    if(yl)
        yl->parent=x;
    x->parent=y;
    if(y->parent==NULL)
        root=y;
}