[LeetCode] Same Tree

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.

用树的遍历来检查。

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (p == NULL && q == NULL)
            return true;
            
        if (p == NULL || q == NULL)
            return false;
            
        bool leftSame = isSameTree(p->left, q->left);
        bool rightSame = isSameTree(p->right, q->right);
        
        return leftSame && rightSame && p->val == q->val;                 
    }
};