def isSubtree(self, s, t):
"""
:type s: TreeNode
:type t: TreeNode
:rtype: bool
"""
def isSameTree(p,q):
if not p and not q:
return True
elif not p and q or (not q and p):
return False
else:
if p.val!=q.val:
return False
else:
return isSameTree(p.left,q.left) and isSameTree(p.right,q.right)
prev=[s]
while prev:
node=prev.pop()
if node:
if isSameTree(node,t):
return True
prev.extend([node.left,node.right])