【LeetCode】100

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.

Solution 1：recursion，the key is to find out all situations of return true and false

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

Solution 2: 非递归，待续