Tag Archives: bfs

C# || Two Sum IV – How To Get Two Numbers In Binary Search Tree Equal To Target Value Using C#

The following is a module with functions which demonstrates how to get two numbers in a binary search tree equal to target value using C#.


1. Find Target – Problem Statement

Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target.

Example 1:

Example 1


Input: root = [5,3,6,2,4,null,7], k = 9
Output: true

Example 2:

Example 2


Input: root = [5,3,6,2,4,null,7], k = 28
Output: false


2. Find Target – Solution

The following are two solutions which demonstrates how to get two numbers in a binary search tree equal to target value.

Both solutions use a set to keep track of the items already seen.

Each time a new node is encountered, we subtract the target value from the current node value. If the difference amount from subtracting the two numbers exists in the set, a 2 sum combination exists in the tree

1. Recursive

The following solution uses Depth First Search when looking for the target value.

2. Iterative

The following solution uses Breadth First Search when looking for the target value.

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:


true
false

C# || How To Traverse N-ary Tree Level Order Using C#

The following is a module with functions which demonstrates how to traverse a N-ary Tree level order using C#.


1. Level Order – Problem Statement

Given an n-ary tree, return the level order traversal of its nodes’ values.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

Example 1:

Example 1


Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]

Example 2:

Example 2


Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]


2. Level Order – Solution

The following is a solution which demonstrates how to traverse a N-ary Tree level order.

This solution uses Breadth First Search to explore items at each level.

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:


[[1],[3,2,4],[5,6]]
[[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]