Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node's descendants. The tree s could also be considered as a subtree of itself.
Example 1:
Given tree s:
3
/
4 5
/
1 2
Given tree t:
4
/
1 2
Return true, because t has the same structure and node values with a subtree of s.
Example 2:
Given tree s:
3
/
4 5
/
1 2
/
0
Given tree t:
4
/
1 2
Return false.
class Solution:
def isSubtree(self, s, t):
"""
:type s: TreeNode
:type t: TreeNode
:rtype: bool
"""
def issame(a,b):
if a is None and b is None:
return True
if a is None or b is None:
return False
if a.val!=b.val:
return False
return issame(a.left,b.left) and issame(a.right,b.right)
if s is None:
return False
if issame(s,t):
return True
return self.isSubtree(s.left,t) or self.isSubtree(s.right,t)