Kata

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

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

length nil # 0
length (1 -> 2 -> 3 -> nil) # 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

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

count nil 1 # 0
count (1 -> 2 -> 3 -> nil) 1 # 1
count (1 -> 1 -> 2 -> 1 -> 2) 2 # 2

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.