Link: https://leetcode.com/problems/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.

思路：遞歸法推斷
假設兩棵樹根結點為p和q

• 假設p和q都為空，則返回true；否則。
• 假設p和q都非空。而且他們的值都相等。則推斷其左右子樹是否是類似樹。否則
• 返回false；

代碼例如以下(C++)：

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