LeetCode100 -- Same Tree--判断两棵二叉树是否相同

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.

思路：利用递归。先判断根节点值是否相等，如果相等再分别判断左子树是否相等和右子树是否相等。

/**
 * Definition for a binary tree node.
 * 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) {
         
         if(p == NULL || q==NULL)
         {
             if(p==NULL && q==NULL)
                return true;
            else 
                return false;
         }
         if(p->val != q->val)
            return false;
         else
            return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
        
    }
};