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 0;
        vector<int> InOrderArray;
        getInOrderArray(InOrderArray, root);
        
 
//INT_MAX定義
        //zhidao.baidu.com/question/294243885.html
        int res = INT_MAX;
        for(int i=1; i<InOrderArray.size(); i++){//遍歷數組得到相鄰兩個元素最小的差
            if(InOrderArray[i] - InOrderArray[i-1] < res)
                res = InOrderArray[i] - InOrderArray[i-1];
        }
        return res;
    }
    
 
void getInOrderArray(vector<int> &InOrderArray, TreeNode* root){//通過中序遍歷得到一個升序數組
        if(!root)
            return;
        getInOrderArray(InOrderArray, root->left);
        InOrderArray.push_back(root->val);
        getInOrderArray(InOrderArray, root->right);
    }

};
int main()
{
    cout << "Hello world!" << endl;
    return 0;
}

Binary Search Tree-530. Minimum Absolute Difference in BST