코드를 자주 읽어봐야 할 필요성을 크게 느껴서 포스팅 🐢
구현하는데 너무 어려웠다.
노드로 값을 확인하고 삭제하고 추가하는게 아직까지도 낯설다 😬
자주 읽어봐야 됨
코드 작성
Node
class Node<T> {
T data;
Node<T> next;
public Node(T data, Node<T> next) {
this.data = data;
this.next = next;
}
}LinkedList
class MyLinkedList<T> {
private Node<T> head;
private int size;
public MyLinkedList() {
this.head = null;
this.size = 0;
}
// add ============================================================================
public T add(T value) {
if (head == null) {
head = new Node<>(value, null );
} else {
Node<T> current = head;
while (current.next != null)
current = current.next;
current.next = new Node<>(value, null);
}
size++;
return value;
}
public T add(int index, T value) {
if (index == 0)
head = new Node<>(value, head);
else if (head == null) {
System.out.printf(
"[ add 실패 : index %d , value %s] 리스트가 비어있음\n",
index,
value
);
return null;
} else if (index > size) {
System.out.printf(
"[ add 실패 : index %d , value %s] index가 list 크기를 벗어남\n",
index,
value
);
return null;
} else {
int idx = 0;
Node<T> prevNode, nextNode;
Node<T> current = head;
while (current != null) {
if (idx + 1 == index) {
prevNode = current;
nextNode = current.next;
prevNode.next = new Node<>(value, nextNode);
break;
}
current = current.next;
idx++;
}
}
size++;
return value;
}
// ============================================================================ add
// remove =========================================================================
public T remove() {
if (head == null) {
System.out.println("[ remove ] 리스트가 이미 비어있음");
return null;
} else {
Node<T> prevNode = head;
Node<T> current = head;
while (current.next != null) {
prevNode = current;
current = prevNode.next;
}
T value = current.data;
if (current == head)
head = null;
else
prevNode.next = null;
size--;
return value;
}
}
public T remove(T value) {
if (head == null) {
System.out.println("[ remove : " + value + " 실패 ] 리스트가 비어있음");
return null;
} else if (!contains(value)) {
System.out.println("[ remove : " + value + " 실패 ] " + value + " 없음");
return null;
} else {
Node<T> prevNode = head;
Node<T> current = head;
while (current != null) {
if (current.data.equals(value)) {
if (current == head)
head = current.next;
else
prevNode.next = current.next;
size--;
break;
}
prevNode = current;
current = prevNode.next;
}
return value;
}
}
// ========================================================================= remove
public boolean contains(T value) {
Node<T> current = head;
while (current != null) {
if (current.data.equals(value))
return true;
current = current.next;
}
return false;
}
public void clear() {
head = null;
size = 0;
}
public boolean isEmpty() {
return head == null;
}
public int size() {
return size;
}
// sout + this.toString =========================================================
public void print() {
System.out.println(this);
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder("LinkedListt : [ ");
if (head == null) {
sb.append("]");
} else {
Node<T> current = head;
do {
sb.append(current.data).append(", ");
current = current.next;
} while (current != null);
sb.deleteCharAt(sb.lastIndexOf(", ")).append("]");
}
sb.append("\n");
sb.append(" size : ").append(size);
sb.append("\n");
return sb.toString();
}
// ========================================================= sout + this.toString
}실행 확인
public class LinkedListt {
public static void main(String[] args) {
MyLinkedList<Integer> list = new MyLinkedList<>();
// linkedList 정보 조회
list.print();
// LinkedListt : [ ]
// size : 0
System.out.println("add : " + list.add(1));
list.print();
// add : 1
// LinkedListt : [ 1 ]
// size : 1
System.out.println("add : " + list.add(2));
list.print();
// add : 2
// LinkedListt : [ 1, 2 ]
// size : 2
System.out.println("add : index 0 , value " + list.add(0, 0));
list.print();
// add : index 0 , value 0
// LinkedListt : [ 0, 1, 2 ]
// size : 3
System.out.println("add : index 4 , value " + list.add(4, 4));
list.print();
// [ add 실패 : index 4 , value 4] index가 list 크기를 벗어남
// add : index 4 , value null
// LinkedListt : [ 0, 1, 2 ]
// size : 3
System.out.println("add : index 3 , value " + list.add(3, 3));
list.print();
// add : index 3 , value 3
// LinkedListt : [ 0, 1, 2, 3 ]
// size : 4
System.out.println("isEmpty : "+ list.isEmpty());
// isEmpty : false
System.out.println("size : "+ list.size());
// size : 4
System.out.println("contains 2 : "+ list.contains(2));
// contains 2 : true
System.out.println("contains 4 : "+ list.contains(4));
// contains 4 : false
System.out.println();
System.out.println("clear");
list.clear();
list.print();
// clear
// LinkedListt : [ ]
// size : 0
System.out.println("isEmpty : "+ list.isEmpty());
System.out.println();
// isEmpty : true
System.out.println("add : index 3 , value " + list.add(3, 2));
list.print();
// [ add 실패 : index 3 , value 2] 리스트가 비어있음
// add : index 3 , value null
// LinkedListt : [ ]
// size : 0
System.out.println("add : index 0 , value " + list.add(0, 11));
list.print();
// add : index 0 , value 11
// LinkedListt : [ 11 ]
// size : 1
System.out.println("add : " + list.add(1));
list.print();
// add : 1
// LinkedListt : [ 11, 1 ]
// size : 2
System.out.println("add : " + list.add(2));
list.print();
// add : 2
// LinkedListt : [ 11, 1, 2 ]
// size : 3
System.out.println("add : index 0 , value " + list.add(0, 0));
list.print();
// add : index 0 , value 0
// LinkedListt : [ 0, 11, 1, 2 ]
// size : 4
System.out.println("add : " + list.add(3));
list.print();
// add : 3
// LinkedListt : [ 0, 11, 1, 2, 3 ]
// size : 5
System.out.println("add : " + list.add(4));
list.print();
// add : 4
// LinkedListt : [ 0, 11, 1, 2, 3, 4 ]
// size : 6
System.out.println("isEmpty : " + list.isEmpty());
System.out.println("remove : " + list.remove(4));
list.print();
// isEmpty : false
// remove : 4
// LinkedListt : [ 0, 11, 1, 2, 3 ]
// size : 5
System.out.println("remove : " + list.remove(2));
list.print();
// remove : 2
// LinkedListt : [ 0, 11, 1, 3 ]
// size : 4
System.out.println("remove : " + list.remove(0));
list.print();
// remove : 0
// LinkedListt : [ 11, 1, 3 ]
// size : 3
System.out.println("remove last : " + list.remove());
list.print();
// remove last : 3
// LinkedListt : [ 11, 1 ]
// size : 2
System.out.println("add : index 0 , value " + list.add(0, 4));
list.print();
// add : index 0 , value 4
// LinkedListt : [ 4, 11, 1 ]
// size : 3
System.out.println("remove last : " + list.remove());
list.print();
// remove last : 1
// LinkedListt : [ 4, 11 ]
// size : 2
System.out.println("remove last : " + list.remove());
list.print();
// remove last : 11
// LinkedListt : [ 4 ]
// size : 1
System.out.println("remove : " + list.remove(11));
list.print();
// [ remove : 11 실패 ] 11 없음
// remove : null
// LinkedListt : [ 4 ]
// size : 1
System.out.println("clear");
list.clear();
list.print();
// clear
// LinkedListt : [ ]
// size : 0
System.out.println("remove : " + list.remove(11));
list.print();
// [ remove : 11 실패 ] 리스트가 비어있음
// remove : null
// LinkedListt : [ ]
// size : 0
}
}
Hello velog!