/**
 * 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 Difference(TreeNode* root,int val){
        if(root==nullptr){
            return INT_MAX;
        }

        if(root->left==nullptr&&root->right==nullptr){
            return INT_MAX;
        }
        if(root->left==nullptr){
            return min(abs(root->right->val-val),Difference(root->right,val));
        }
        if(root->right==nullptr){
            return min(abs(root->left->val-val),Difference(root->left,val));
        }

        return min(abs(root->left->val-val),
                   min(abs(val-root->right->val),
                    min(Difference(root->right,val),Difference(root->left,val))));

    }

    int mini=INT_MAX;

    int getMinimumDifference(TreeNode* root) {

        if(root==nullptr){
            return INT_MAX;
        }

        if(root->left==nullptr&&root->right==nullptr){
            return INT_MAX;
        }
        if(root->left==nullptr){
            return min(mini,min(Difference(root->right,root->right->val)
                                ,Difference(root,root->val)));
        }
        if(root->right==nullptr){
            return min(mini,min(Difference(root->left,root->left->val),
                Difference(root,root->val)));
        }

        return min(min(Difference(root,root->val),mini),
                   min(Difference(root->left,root->left->val),Difference(root->right,root->right->val)));
    }
};