LeetCode 965. 单值二叉树(二叉树的遍历)

单值二叉树

/**
 * 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:
    int n ;
    bool isUnivalTree(TreeNode* root) {
        n = root->val;
        return preOrder(root);
    }
    bool preOrder(TreeNode* root){
        if(!root){
            return true;
        }
        if(root->val != n){
            return false;
        }
        if(!preOrder(root->left) || !preOrder(root->right)){
            return false;
        }
        return true;
    }
};