problems: add „108. Convert Sorted Array to Binary Search Tree“

Signed-off-by: Matej Focko <mfocko@redhat.com>

.pre-commit-config.yaml

@@ -2,7 +2,7 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.2.0
+    rev: v4.3.0
     hooks:
     -   id: trailing-whitespace
     -   id: end-of-file-fixer

problems/convert-sorted-array-to-binary-search-tree.java

@@ -0,0 +1,33 @@
+/**
+ * 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 {
+    private TreeNode sortedArrayToBST(int[] nums, int min, int max) {
+        if (min > max) {
+            return null;
+        }
+
+        int mid = (min + max) / 2;
+        return new TreeNode(
+            nums[mid],
+            sortedArrayToBST(nums, min, mid - 1),
+            sortedArrayToBST(nums, mid + 1, max)
+        );
+    }
+
+    public TreeNode sortedArrayToBST(int[] nums) {
+        return sortedArrayToBST(nums, 0, nums.length - 1);
+    }
+}