572. 另一棵树的子树

572. 另一棵树的子树
     

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
        #判断是否是子树，主要分为两步：根节点的判断，树形状的判断
        def hasSameTree(tmpRoot, tmpSubRoot):
            if not tmpRoot and not tmpSubRoot:
                return True
            if not tmpRoot or not tmpSubRoot:
                return False
            if tmpRoot.val == tmpSubRoot.val:
                return hasSameTree(tmpRoot.left, tmpSubRoot.left) and hasSameTree(tmpRoot.right, tmpSubRoot.right)
            return False
        if root:
            if hasSameTree(root, subRoot):
                return True
            return self.isSubtree(root.left, subRoot) or self.isSubtree(root.right, subRoot)
        return False