# Find the Minimum Absolute Difference in BST using Java ## The question

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.

## The solution

```.wp-block-code{border:0;padding:0}.wp-block-code>div{overflow:auto}.shcb-language{border:0;clip:rect(1px,1px,1px,1px);-webkit-clip-path:inset(50%);clip-path:inset(50%);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;word-wrap:normal;word-break:normal}.hljs{box-sizing:border-box}.hljs.shcb-code-table{display:table;width:100%}.hljs.shcb-code-table>.shcb-loc{color:inherit;display:table-row;width:100%}.hljs.shcb-code-table .shcb-loc>span{display:table-cell}.wp-block-code code.hljs:not(.shcb-wrap-lines){white-space:pre}.wp-block-code code.hljs.shcb-wrap-lines{white-space:pre-wrap}.hljs.shcb-line-numbers{border-spacing:0;counter-reset:line}.hljs.shcb-line-numbers>.shcb-loc{counter-increment:line}.hljs.shcb-line-numbers .shcb-loc>span{padding-left:.75em}.hljs.shcb-line-numbers .shcb-loc::before{border-right:1px solid #ddd;content:counter(line);display:table-cell;padding:0 .75em;text-align:right;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;white-space:nowrap;width:1%}```/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode() {}
*     TreeNode(int val) { this.val = val; }
*     TreeNode(int val, TreeNode left, TreeNode right) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/
class Solution {
public int getMinimumDifference(TreeNode root) {

}
}```Code language: Java (java)```

Of this, the meat really comes in with the `getMinimumDifference` method.

So let’s use Depth First Search (`DFS`) to solve this problem.

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode() {}
*     TreeNode(int val) { this.val = val; }
*     TreeNode(int val, TreeNode left, TreeNode right) {
*         this.val = val;
*         this.left = left;
*         this.right = right;
*     }
* }
*/
class Solution {
// Store our list of points
public List<Integer> list = new ArrayList<>();
// Store the max differences
public int dif = Integer.MAX_VALUE;

// Our DFS method
public void dfs(TreeNode root) {
// return if not exists
if(root == null) return;
// recurse left
dfs(root.left);
// recurse right
dfs(root.right);
}
// Main entry point, takes in the TreeNode's root
public int getMinimumDifference(TreeNode root) {
// do our DFS on the tree
dfs(root);

// loop through our `list`
for(int i=1;i<list.size();i++) {
// primary conditional
if(Math.abs(list.get(i) - list.get(i - 1)) < dif)
// set the difference int
dif = Math.abs(list.get(i) - list.get(i - 1));
}
// Return the difference as an integer
return dif;
}
}
```Code language: Java (java)```
Subscribe
Notify of 