leetcode 100. Same Tree、101. Symmetric Tree

 100. Same Tree

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

 

101. Symmetric Tree

/**
 * 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 isSymmetric(TreeNode* root) {
        if(!root)
            return true;
        return isSymmetric(root,root);
    }
    bool isSymmetric(TreeNode* left,TreeNode* right){
        if(!left && !right)
            return true;
        if(!left || !right)
            return false;
        if(left->val != right->val)
            return false;
        return isSymmetric(left->left,right->right) && isSymmetric(left->right,right->left);
    }
};