// Closest Binary Search Tree Value
class Solution {
public:
  int closestValue(TreeNode *x, double target) {
    int opt;
    double optd = numeric_limits<double>::max();
    while (x) {
      double d = fabs(target-x->val);
      if (d < optd)
        optd = d, opt = x->val;
      x = target < x->val ? x->left : x->right;
    }
    return opt;
  }
};