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Commit cdc00f1

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Singly linked list
1 parent 759c4d3 commit cdc00f1

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3 files changed

+160
-4
lines changed

3 files changed

+160
-4
lines changed

‎src/main/kotlin/pl/dmichalski/algorithms/data_structures/_1_singly_linked_list/Node.kt‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
package pl.dmichalski.algorithms.data_structures._1_singly_linked_list
22

3-
class Node(private val value: String) {
3+
class Node(private var value: String) {
44

55
private var next: Node?
66

@@ -12,6 +12,10 @@ class Node(private val value: String) {
1212
return value
1313
}
1414

15+
fun setValue(value: String) {
16+
this.value = value
17+
}
18+
1519
fun getNext(): Node? {
1620
return next
1721
}
@@ -20,4 +24,9 @@ class Node(private val value: String) {
2024
next = nextNode
2125
}
2226

27+
override fun toString(): String {
28+
return "Node(value='$value', next=$next)"
29+
}
30+
31+
2332
}

‎src/main/kotlin/pl/dmichalski/algorithms/data_structures/_1_singly_linked_list/Runner.kt‎

Lines changed: 53 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -4,17 +4,67 @@ object Runner {
44

55
@JvmStatic
66
fun main(args: Array<String>) {
7-
val singlyLinkedList = SinglyLinkedList()
7+
println("------------------ Initial linked list ------------------ ")
8+
var singlyLinkedList = getSinglyLinkedLit()
9+
printList(singlyLinkedList)
810

9-
singlyLinkedList.push("first")
10-
singlyLinkedList.push("second")
11+
println("------------------ After adding third element to the end ------------------ ")
12+
singlyLinkedList= getSinglyLinkedLit()
1113
singlyLinkedList.push("third")
14+
printList(singlyLinkedList)
1215

16+
println("------------------ After removing last element ------------------ ")
17+
singlyLinkedList = getSinglyLinkedLit()
1318
singlyLinkedList.pop()
19+
printList(singlyLinkedList)
1420

21+
println("------------------ After removing first element ------------------ ")
22+
singlyLinkedList = getSinglyLinkedLit()
1523
singlyLinkedList.shift()
24+
printList(singlyLinkedList)
1625

26+
println("------------------ After adding element to the beginning ------------------ ")
27+
singlyLinkedList = getSinglyLinkedLit()
1728
singlyLinkedList.unshift("before first")
29+
printList(singlyLinkedList)
30+
31+
println("------------------ Getting the last element ------------------")
32+
singlyLinkedList = getSinglyLinkedLit()
33+
val lastElement = singlyLinkedList.get(singlyLinkedList.getLength() - 1)
34+
println("lastElement = ${lastElement}")
35+
36+
println("\n------------------ Setting new first element ------------------ ")
37+
singlyLinkedList = getSinglyLinkedLit()
38+
singlyLinkedList.set("new first", 0)
39+
printList(singlyLinkedList)
40+
41+
println("------------------ Insert element to the beginning ------------------ ")
42+
singlyLinkedList = getSinglyLinkedLit()
43+
singlyLinkedList.insert("before first", 0)
44+
printList(singlyLinkedList)
45+
46+
println("------------------ Removing first element ------------------ ")
47+
singlyLinkedList = getSinglyLinkedLit()
48+
singlyLinkedList.remove(0)
49+
printList(singlyLinkedList)
50+
51+
println("------------------ Revering the list ------------------ ")
52+
singlyLinkedList = getSinglyLinkedLit()
53+
singlyLinkedList.reverse()
54+
printList(singlyLinkedList)
55+
}
56+
57+
private fun getSinglyLinkedLit(): SinglyLinkedList {
58+
val singlyLinkedList = SinglyLinkedList()
59+
60+
singlyLinkedList.push("first")
61+
singlyLinkedList.push("second")
62+
63+
return singlyLinkedList;
64+
}
65+
66+
private fun printList(singlyLinkedList: SinglyLinkedList) {
67+
println(singlyLinkedList)
1868
}
1969

2070
}

‎src/main/kotlin/pl/dmichalski/algorithms/data_structures/_1_singly_linked_list/SinglyLinkedList.kt‎

Lines changed: 97 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -72,6 +72,98 @@ class SinglyLinkedList {
7272
length++
7373
}
7474

75+
fun get(index: Int): Node? {
76+
if (index < 0 || index >= length) {
77+
return null
78+
}
79+
80+
var currentIndex = 0
81+
var current = head
82+
83+
while (currentIndex != index) {
84+
current = current!!.getNext()
85+
currentIndex++
86+
}
87+
88+
return current
89+
}
90+
91+
fun set(value: String, index: Int): Boolean {
92+
val node = get(index)
93+
return if (node != null) {
94+
node.setValue(value)
95+
true
96+
} else {
97+
false
98+
}
99+
}
100+
101+
fun insert(value: String, index: Int): Boolean {
102+
if (index < 0 || index > length) {
103+
return false
104+
}
105+
106+
if (index == 0) {
107+
this.unshift(value)
108+
return true
109+
}
110+
111+
if (index == length) {
112+
this.push(value)
113+
return true
114+
}
115+
116+
val previous = this.get(index - 1)
117+
118+
val newNode = Node(value)
119+
newNode.setNext(previous!!.getNext())
120+
previous.setNext(newNode)
121+
length++
122+
return true
123+
}
124+
125+
fun remove(index: Int): Node? {
126+
if (index < 0 || index >= length) {
127+
return null
128+
}
129+
130+
if (index == 0) {
131+
val firstElement = head
132+
shift()
133+
return firstElement
134+
}
135+
136+
if (index == length - 1) {
137+
val lastElement = tail
138+
pop()
139+
return lastElement
140+
}
141+
142+
val previous = get(index - 1)
143+
val elementToRemove = previous!!.getNext()
144+
previous.setNext(elementToRemove!!.getNext())
145+
length--
146+
return elementToRemove
147+
}
148+
149+
fun reverse(): SinglyLinkedList {
150+
var currentNode = this.head
151+
this.head = this.tail
152+
this.tail = currentNode
153+
154+
var previous: Node? = null
155+
var nextNode: Node?
156+
157+
for (i in 0 until length) {
158+
nextNode = currentNode?.getNext()
159+
currentNode!!.setNext(previous)
160+
previous = currentNode
161+
currentNode = nextNode
162+
}
163+
164+
return this
165+
}
166+
75167
fun getHead(): Node? {
76168
return head
77169
}
@@ -84,4 +176,9 @@ class SinglyLinkedList {
84176
return length
85177
}
86178

179+
override fun toString(): String {
180+
return "Head: $head\n" +
181+
"Tail: $tail\n" +
182+
"Length: $length\n"
183+
}
87184
}

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