### Problem Statement :

```Given the pointer to the head node of a linked list, change the next pointers of the nodes so that their order is reversed. The head pointer given may be null meaning that the initial list is empty.

Example:

Manipulate the next pointers of each node in place and return head, now referencing the head of the list 3->2->1->Null.

Function Description:

Complete the reverse function in the editor below.

reverse has the following parameter:
Returns

Input Format:

The first line contains an integer t, the number of test cases.
Each test case has the following format:
1. The first line contains an integer n, the number of elements in the linked list.
2. Each of the next n lines contains an integer, the data values of the elements in the linked list.

Constraints:
1.   1<=t<=10
2.   1<=n<=1000
3.   1<=list[i]<=1000```

### Solution :

```                            ```Solution in C :

In C:

//the following function is all that is needed to complete the
//challenge in hackerrank platform.

}

}

In C++:

//the following function is all that is needed to complete the
//challenge in hackerrank platform.

{
// Complete this method
Node* prev   = NULL;
Node* next;

while (current != NULL)
{
next  = current->next;
current->next = prev;
prev = current;
current = next;
}

return prev;
}

In Java:

//the following method is all that is needed to complete the
//challenge in hackerrank platform.

while(current!=null)
{
next = current.next;
current.next = previous;
previous = current;
current = next;
}
}

In Python 3:

//the following method is all that is needed to complete the
//challenge in hackerrank platform.

prev = None
next = None
while current is not None:
next = current.next
current.next = prev;
prev = current;
current = next;

return prev```
```

## Tree: Height of a Binary Tree

The height of a binary tree is the number of edges between the tree's root and its furthest leaf. For example, the following binary tree is of height : image Function Description Complete the getHeight or height function in the editor. It must return the height of a binary tree as an integer. getHeight or height has the following parameter(s): root: a reference to the root of a binary

## Tree : Top View

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## Tree: Level Order Traversal

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## Binary Search Tree : Insertion

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## Tree: Huffman Decoding

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## Binary Search Tree : Lowest Common Ancestor

You are given pointer to the root of the binary search tree and two values v1 and v2. You need to return the lowest common ancestor (LCA) of v1 and v2 in the binary search tree. In the diagram above, the lowest common ancestor of the nodes 4 and 6 is the node 3. Node 3 is the lowest node which has nodes and as descendants. Function Description Complete the function lca in the editor b