Leetcode 100. Same Tree

题目

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.

分析

比较两个二叉树是否相等，依次判断根节点和左右子数是否相同，使用递归即可，可能递归带来的函数调用花费时间较多一些，但是所有节点只判断了一次。

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

bool isSameTree(struct TreeNode* p, struct TreeNode* q) {
    return sameTree(p,q);
}