109 lines
2.3 KiB
CoffeeScript
109 lines
2.3 KiB
CoffeeScript
# "Classic" linked list implementation that doesn't keep track of its size.
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class LinkedList
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->
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this._head = null # Pointer to the first item in the list.
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# Appends some data to the end of the list. This method traverses the existing
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# list and places the value at the end in a new node.
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add: (data) ->
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# Create a new node object to wrap the data.
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node = data: data, next: null
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current = this._head or= node
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if this._head isnt node
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(current = current.next) while current.next
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current.next = node
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this
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# Retrieves the data at the given position in the list.
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item: (index) ->
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# Check for out-of-bounds values.
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return null if index < 0
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current = this._head or null
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i = -1
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# Advance through the list.
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(current = current.next) while current and index > (i += 1)
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# Return null if we've reached the end.
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current and current.data
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# Remove the item from the given location in the list.
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remove: (index) ->
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# Check for out-of-bounds values.
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return null if index < 0
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current = this._head or null
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i = -1
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# Special case: removing the first item.
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if index is 0
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this._head = current.next
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else
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# Find the right location.
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([previous, current] = [current, current.next]) while index > (i += 1)
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# Skip over the item to remove.
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previous.next = current.next
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# Return the value.
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current and current.data
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# Calculate the number of items in the list.
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size: ->
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current = this._head
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count = 0
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while current
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count += 1
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current = current.next
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count
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# Convert the list into an array.
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toArray: ->
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result = []
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current = this._head
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while current
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result.push current.data
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current = current.next
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result
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# The string representation of the linked list.
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toString: -> this.toArray().toString()
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# Tests.
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list = new LinkedList
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list.add("Hi")
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console.log list.size() is 1
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console.log list.item(0) is "Hi"
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console.log list.item(1) is null
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list = new LinkedList
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list.add("zero").add("one").add("two")
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console.log list.size() is 3
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console.log list.item(2) is "two"
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console.log list.remove(1) is "one"
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console.log list.item(0) is "zero"
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console.log list.item(1) is "two"
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console.log list.size() is 2
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console.log list.item(-10) is null
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