Given a Binary Search Tree (BST) with the root node root, return the minimum difference between the values of any two different nodes in the tree.
Example :
Input: root = [4,2,6,1,3,null,null] Output: 1 Explanation: Note that root is a TreeNode object, not an array.
The given tree [4,2,6,1,3,null,null] is represented by the following diagram:
4 / \ 2 6 / \ 1 3
while the minimum difference in this tree is 1, it occurs between node 1 and node 2, also between node 3 and node 2. Note:
The size of the BST will be between 2 and 100. The BST is always valid, each node's value is an integer, and each node's value is different.
/**
* Definition for a binary tree node.
* public class TreeNode {
* public int val;
* public TreeNode left;
* public TreeNode right;
* public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
public class Solution {
int min=int.MaxValue;
int? prev = null;
public int MinDiffInBST(TreeNode root) {
Helper(root);
return min;
}
private void Helper(TreeNode root){
if(root==null){
return;
}
Helper(root.left);
if(prev!=null){
min = Math.Min(min,root.val-(int)prev);
}
prev = root.val;
Helper(root.right);
}
}Time Complexity: O(n)
Space Complexity: O(1)
