LeetCode 100. Same Tree

100. Same Tree

Descripiton

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

• 题意即判断两个二叉树是否相同，要求结构相同并且对应位置的节点值也相等。
• 用递归很容易实现，对空节点的几种情况特判之后，判断当前节点值是否相同、左子树和右子树是否相同。代码如下。

class Solution {public:    bool isSameTree(TreeNode* p, TreeNode* q) {        if (p == NULL && q == NULL) return true;        if ((p == NULL && q != NULL) || (p != NULL && q == NULL)) return false;        if (p->val == q->val && isSameTree(p->left,q->left) && isSameTree(p->right,q->right))             return true;        else             return false;    }};