Check if subtree

/*
Logic:
isSubTree function will traverse the tree and where root->node of subtree matches with
current node of tree,then fun will be called which will check for subtree after current
node matches or not.

T.C O(mn) m,n is no. of nodes in both trees.
S.C O(n)

*/
bool fun(Node *t,Node *s){
    if(!t && !s) return true;
    if(!t || !s) return false;
    if(t->data==s->data)
       return (fun(t->left,s->left) && fun(t->right,s->right));
    else return false;
}
class Solution
{
  public:
    //Function to check if S is a subtree of tree T.
    bool isSubTree(Node* t, Node* s)
    {
        if(!t && !s) return true;
        if(!t || !s) return false;
        if(t->data==s->data && fun(t,s)) return true;
        return isSubTree(t->left,s) || isSubTree(t->right,s);
    }
};

//Method 2:
/*
 TC O(n)
 SC O(m+n)
 find preorder and inorder of both tree and if preorder of subtree is subarray of actual tree && inorder of subtree
 is subarray of actual tree,return true else false;
 use KMP for string matching.

*/