100. Same Tree

Problem:

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.

 

Analysis:

recursion

 

A possible answer:

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