Binary Search Tree-530. Minimum Absolute Difference in BST

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.

Example:

Input:

   1
    \
     3
    /
   2

Output:
1

Explanation:
The minimum absolute difference is 1, which is the difference between 2 and 1 (or between 2 and 3).

Note: There are at least two nodes in this BST.

#include <iostream>
#include <vector>
#include <limits.h>
using namespace std;

class Solution {
public:
    int getMinimumDifference(TreeNode* root) {
        if(!root)
            return ;
        vector<int> InOrderArray;
        getInOrderArray(InOrderArray, root);
        //INT_MAX定义
        //zhidao.baidu.com/question/294243885.html
        int res = INT_MAX;
        for(int i=; i<InOrderArray.size(); i++){//遍历数组得到相邻两个元素最小的差
            if(InOrderArray[i] - InOrderArray[i-] < res)
                res = InOrderArray[i] - InOrderArray[i-];
        }
        return res;
    }
    void getInOrderArray(vector<int> &InOrderArray, TreeNode* root){//通过中序遍历得到一个升序数组
        if(!root)
            return;
        getInOrderArray(InOrderArray, root->left);
        InOrderArray.push_back(root->val);
        getInOrderArray(InOrderArray, root->right);
    }

};
int main()
{
    cout << "Hello world!" << endl;
    return ;
}