Linked Lists - Length & Count

Linked Lists - Length & Count

Linked Lists - Length & Count

Implement Length() to count the number of nodes in a linked list.

length(null) => 0
length(1 -> 2 -> 3 -> null) => 3

Node.Length(nullptr) => 0
Node.Length(1 -> 2 -> 3 -> nullptr) => 3

length(null) => 0
length(1 -> 2 -> 3 -> null) => 3

Implement Count() to count the occurrences of an integer in a linked list.

count(null, 1) => 0
count(1 -> 2 -> 3 -> null, 1) => 1
count(1 -> 1 -> 1 -> 2 -> 2 -> 2 -> 2 -> 3 -> 3 -> null, 2) => 4

Node.Count(null, value => value == 1) => 0
Node.Count(1 -> 3 -> 5 -> 6, value => value % 2 != 0) => 3

count(null, 1) => 0
count(1 -> 2 -> 3 -> nullptr, 1) => 1
count(1 -> 1 -> 1 -> 2 -> 2 -> 2 -> 2 -> 3 -> 3 -> nullptr, 2) => 4

I've decided to bundle these two functions within the same Kata since they are both very similar.

The push()/Push() and buildOneTwoThree()/BuildOneTwoThree() functions do not need to be redefined.

Related Kata in order of expected completion (increasing difficulty): Linked Lists - Push & BuildOneTwoThree Linked Lists - Length & Count Linked Lists - Get Nth Node Linked Lists - Insert Nth Node Linked Lists - Sorted Insert Linked Lists - Insert Sort Linked Lists - Append Linked Lists - Remove Duplicates Linked Lists - Move Node Linked Lists - Move Node In-place Linked Lists - Alternating Split Linked Lists - Front Back Split Linked Lists - Shuffle Merge Linked Lists - Sorted Merge Linked Lists - Merge Sort Linked Lists - Sorted Intersect Linked Lists - Iterative Reverse Linked Lists - Recursive Reverse

Inspired by Stanford Professor Nick Parlante's excellent Linked List teachings.

Solutions

🧠 C++

/* Node Definition
struct Node {
  Node * next;
  int data;
}
*/

int Length(Node *head)
{
  int counter = 0;
  for(;head!=nullptr;head=head->next)
    ++counter;
  return counter;
}

int Count(Node *head, int data)
{
  int counter = 0;
  for(;head!=nullptr;head=head->next)
    if(head->data==data) ++counter;
  return counter;
}