题目链接/文章讲解：https://programmercarl.com/0530.%E4%BA%8C%E5%8F%89%E6%90%9C%E7%B4%A2%E6%A0%91%E7%9A%84%E6%9C%80%E5%B0%8F%E7%BB%9D%E5%AF%B9%E5%B7%AE.html

视频讲解：https://www.bilibili.com/video/BV1DD4y11779

1.今天这个题又帮我复习了一下昨天的双指针的习题，真的让我受益匪浅，对于这个双指针以及迭代的思路有了更进一步的清晰地认识。

CPP

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int res = INT_MAX;
    TreeNode*pre = NULL;
    void traversal(TreeNode* cur){
        if(cur == NULL)return;
        traversal(cur->left);
        
        if(pre != NULL){
            res = min(res,cur->val - pre->val);
        }
        pre = cur;

        traversal(cur->right);
    }
    int getMinimumDifference(TreeNode* root) {
        traversal(root);
        return res;
    }
};