C# || How To Convert Sorted Array To Binary Search Tree Using C#

October 18, 2021 admin No comments

The following is a module with functions which demonstrates how to convert a sorted array to a binary search tree using C#.

1. Sorted Array To BST – Problem Statement

Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.

A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.

Example 1:

Input: nums = [-10,-3,0,5,9] Output: [0,-3,9,-10,null,5] Explanation: [0,-10,5,null,-3,null,9] is also accepted:

Example 2:

Input: nums = [1,3] Output: [3,1] Explanation: [1,3] and [3,1] are both a height-balanced BSTs.

2. Sorted Array To BST – Solution

The following is a solution which demonstrates how to convert a sorted array to a binary search tree.





		
		
			2. Sorted Array To BST - Solution
			
C#
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Oct 18, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Solution.cs
//    Description: Demonstrates how to convert sorted array to BST
// ============================================================================
/**
 * 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 {
    public TreeNode SortedArrayToBST(int[] nums) {
        return BuildBST(nums, 0, nums.Length -1);
    }

    TreeNode BuildBST(int[] nums, int start, int end) {
        if (start > end) {
            return null;
        }

        var mid = start + (end - start) / 2;
        var node = new TreeNode(nums[mid]);
        node.left = BuildBST(nums, start, mid - 1);
        node.right = BuildBST(nums, mid + 1, end);
        return node;
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Oct 18, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Solution.cs
//    Description: Demonstrates how to convert sorted array to BST
// ============================================================================
/**
 * 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 {
    public TreeNode SortedArrayToBST(int[] nums) {
        return BuildBST(nums, 0, nums.Length -1);
    }
 
    TreeNode BuildBST(int[] nums, int start, int end) {
        if (start > end) {
            return null;
        }
 
        var mid = start + (end - start) / 2;
        var node = new TreeNode(nums[mid]);
        node.left = BuildBST(nums, start, mid - 1);
        node.right = BuildBST(nums, mid + 1, end);
        return node;
    }
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output for the example cases:

[0,-10,5,null,-3,null,9] [1,null,3]

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Posted in: C#, Console Tags: binary tree, c-sharp, leetcode

C# || How To Convert Sorted Array To Binary Search Tree Using C#

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