leetcode Question 90: Same Tree

Same Tree:

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

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

Analysis:

Recursively check the left child and right child.  If the value is different, or if one of the two nodes is null, return false.

Code(C++):

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isSameTree(TreeNode *p, TreeNode *q) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (!p && !q) {return true;}
        if ((!p && q) || (!q && p)){return false;}
        if (p->val!=q->val){return false;}
        return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
    }
};

Code(Python):

# Definition for a  binary tree node
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    # @param p, a tree node
    # @param q, a tree node
    # @return a boolean
    def isSameTree(self, p, q):
        if p == None and q == None:
            return True
        elif p == None and q != None:
            return False
        elif p != None and q == None:
            return False
        elif p.val != q.val:
            return False
        else:
            return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)