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.
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
TreeSet<Integer> set = new TreeSet<>();
int min = Integer.MAX_VALUE;
public int getMinimumDifference(TreeNode root) {
if (root == null) return min;
if (!set.isEmpty()) {
if (set.floor(root.val) != null) {
min = Math.min(min, root.val - set.floor(root.val));
}
if (set.ceiling(root.val) != null) {
min = Math.min(min, set.ceiling(root.val) - root.val);
}
}
set.add(root.val);
getMinimumDifference(root.left);
getMinimumDifference(root.right);
return min;
}
}