README.md

100. Same Tree

Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input: 1 1 / \ / \ 2 3 2 3 [1,2,3], [1,2,3] Output: true 

Example 2:

Input: 1 1 / \ 2 2 [1,2], [1,null,2] Output: false 

Example 3:

Input: 1 1 / \ / \ 2 1 1 2 [1,2,1], [1,1,2] Output: false 

Solutions (Python)

1. Recursion

# Definition for a binary tree node.# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = NoneclassSolution: defisSameTree(self, p: TreeNode, q: TreeNode) ->bool: ifnotpandnotq: returnTrueifnotpornotqorp.val!=q.val: returnFalsereturnself.isSameTree(p.left, q.left) andself.isSameTree(p.right, q.right)

2. Iteration

# Definition for a binary tree node.# class TreeNode:# def __init__(self, x):# self.val = x# self.left = None# self.right = NoneclassSolution: defisSameTree(self, p: TreeNode, q: TreeNode) ->bool: stackp, stackq= [p], [q] whilestackp: nodep, nodeq=stackp.pop(), stackq.pop() ifnotnodepandnotnodeq: continueifnotnodepornotnodeqornodep.val!=nodeq.val: returnFalsestackp.append(nodep.left) stackq.append(nodeq.left) stackp.append(nodep.right) stackq.append(nodeq.right) returnTrue