LeetCode 270: Closest Binary Search Tree Value

BST. Left node value < root value < right node value.

/*
  Given a non-empty binary search tree and a target value, find the value in BST
  that is closest to the target.
  Note:
  1: Given target value is a floating point.
  2: You are guranteed to have only one unique value in BST that is closest to the target.
*/

// Because it is BST, we are going to use the BST feature.
int closestValue(TreeNode* root, double target) {
  int minDistance = INT_MAX;
  int tmp = root->val;
  while(root) {
    int distance = abs(root->val - target);
    if(distance < minDistance) {
      minDistance = distance;
      tmp = root->val;
    }
    if(root->val > target) root = root->left;
    else if(root->val < target) root = root->right;
    else return root->val;
  }
  return tmp;
}