100. Same Tree

#100. Same Tree
#   这道题有两种方法。第一种是用递归的方法，一个一个的比较，只要不相等就直接返回False。这种方法比较慢
class Solution:
    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """
        if not p and not q:
            return True

        if not p or not q:
            return False

        if p and q and p.val == q.val:
            left = self.isSameTree(p.left, q.left)
            right = self.isSameTree(p.right, q.right)
            return left and right

        return False

# 第二种方法是用 level order 的方法把 tree 转化成array然后进行比较
from collections import deque
class Solution2:
    def inorder(self, root, res):
        q = deque()
        q.append(root)
        while q:
            num = len(q)
            for i in range(0, num):
                node = q.popleft()
                if node:
                    res.append(node.val)
                    if node.left:
                        q.append(node.left)
                    else:
                        q.append(None)
                    if node.right:
                        q.append(node.right)
                    else:
                        q.append(None)
                else:
                    res.append(node)

    def isSameTree(self, p, q):
        """
        :type p: TreeNode
        :type q: TreeNode
        :rtype: bool
        """

        res1 = []
        res2 = []
        self.inorder(p, res1)
        self.inorder(q, res2)

        if len(res1) != len(res2):
            return False
        else:
            for i in range(0, len(res1)):
                if res1[i] != res2[i]:
                    return False
            return True