add code of 108

Author: Li Li

Algorithms Basics/top-interview-questions/108. Convert Sorted Array to Binary Search Tree.cs

@@ -0,0 +1,15 @@
+// keep in mind, if transform a array to BST, just sort the array first.
+public class Solution {
+    public TreeNode SortedArrayToBST(int[] nums) {
+        if (nums == null || nums.Length == 0) return null;
+        return SortedArrayToBST(nums, 0, nums.Length - 1);
+    }
+    private TreeNode SortedArrayToBST(int[] nums, int left, int right) {
+        if (left > right) return null;
+        int mid = left + (right - left) / 2;
+        TreeNode root = new TreeNode(nums[mid]);
+        root.left = SortedArrayToBST(nums, left, mid - 1);
+        root.right = SortedArrayToBST(nums, mid + 1, right);
+        return root;
+    }
+}