LeetCode No.100 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.

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題目鏈接：https://leetcode.com/problems/same-tree/

題目大意：判斷兩棵樹是否相等。

思路：遞歸。

參考代碼：

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