572. Subtree Of Another Tree

Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false otherwise.

A subtree of a binary tree tree is a tree that consists of a node in tree and all of this node’s descendants. The tree tree could also be considered as a subtree of itself.

class Solution:
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if p is None and q is None: return True
        if p is None or q is None: return False
 
        if p.val != q.val:
            return False
        
        return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)
 
    def isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
        # base cases
        if root is None and subRoot is None:
            return True
        if root is None or subRoot is None:
            return False
 
        if root.val == subRoot.val:
            if self.isSameTree(root, subRoot):
                return True
        return self.isSubtree(root.left, subRoot) or self.isSubtree(root.right, subRoot)

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Related.

• 100-same-tree.

References.

Categories:: tree, binary-tree, recursion