LeetCode - 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.

http://oj.leetcode.com/problems/same-tree/

Solution:

First check NULL case, then recursively check every node

https://github.com/starcroce/leetcode/blob/master/same_tree.cpp

// 20 ms for 52 test cases
/**
 * 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 == NULL){
            return q == NULL;
        }
        else{
            if(q == NULL){
                return false;
            }
            else{
                if(p->val != q->val){
                    return false;
                }
                bool left_same = isSameTree(p->left, q->left);
                if(!left_same){
                    return false;
                }
                return isSameTree(p->right, q->right);
            }
        }
    }
};