LeetCode——same-tree

Question

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

递归判断，首先要判断结构是否一样，如果不一样直接返回false，如果结构一样，那么要继续判断值是否相等，如果不等直接返回false，如果相等，那么继续遍历左子树和右子树。

Code

/**
 * Definition for binary tree
 * 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)
            return false;
        if (q == NULL)
            return false;
        if (p->val == q->val) {
             return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
        } else
            return false;
    }
};