LeetCode 100. Same Tree C语言

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.

树的问题最容易想到的是用递归；

一颗二叉树相同是它的根节点相同和左右子树相同；

左右子树是否相同也一样这样想；

特殊情况是两棵树都为空，还有其中一棵树为空；

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