LeetCode--Same Tree

题目:

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.

代码:

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */

    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(p == NULL && q == NULL)
        {
            return true;
        }
        else if(p == NULL && q != NULL)
        {
            return false;
        }
        else if( p != NULL && q == NULL)
        {
            return false;
        }
        else
        {
            if(p->val == q->val)
            {
               return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
            }
            else
                return false;
        }
    }