Sword refers to the substructure of an offer tree (Python) __python

Topic description

Enter two binary tree a,b to determine whether B is a sub structure. (PS: We agreed that an empty tree is not a substructure of any tree)

Ideas:

Consider using recursive completion, a function nesting recursion to determine whether to match to the starting node, and another to write a recursive to determine whether the right subtree of Saozi is a substructure function.

1, to determine the beginning of a current node, B is a substructure, if not look at the left subtree of a node, if it is not to look at the right subtree of a.

2, if a node starts A and B to coincide with the starting node:

① to determine if B is matched, if the match is finished the description is a substructure

② If a match is over, or the value of a is unequal to B and value, return false directly

③ If the current point is the same, look at the Saozi right subtree at the same time.

The code is as follows:

#-*-Coding:utf-8-*-
"" "
topic Description:
input Two binary tree a,b, Judge B is not a substructure. (PS: We agreed that an empty tree is not a substructure of any tree) ""
Class TreeNode ():
    def __init__ (self,x):
        self.val = x
        self.left = None
        self.right = None        
def hassubtree (proot1,proot2):
    if not pRoot1 or PRoot2: return
        False
    return Is_subtree (Proot1,proot2) or Hassubtree (Proot1.left,proot2) or Hassubtree (proot1.right,proot2)
def is_Subtree ( A,B):
    if not B: return
        True
    if not A/a.val!= b.val: Return
        False return
    is_subtree (a.left,b. left) and Is_subtree (A.right,b.right)