* Definition for a binary tree node.
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
int getMinimumDifference(TreeNode* root) {
int m=std::numeric_limits<int>::max();
TreeNode* leftNode=root->left;
ld=root->val - leftNode->val;
leftNode=leftNode->right;
TreeNode* rightNode=root->right;
rd=rightNode->val-root->val;
rightNode=rightNode->left;
// cout<<ld << " " <<rd << " "<< m<<endl;
if(root->left&& root->right)
m=min(m,min(getMinimumDifference(root->left),getMinimumDifference(root->right)));
m=min(ld,getMinimumDifference(root->left));
else if(root->right) m=min(rd,getMinimumDifference(root->right));