单链表反转(Singly Linked Lists in Java)

单链表反转(Singly Linked Lists in Java)

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数据结构及算法

Java代码


package dsa.linkedlist;

public class Node<E>{

E data;

Node<E> next;

}

Java代码


package dsa.linkedlist;

public class ReverseLinkedListRecursively {

public static void main(String args[]) {

ReverseLinkedListRecursively reverser = new ReverseLinkedListRecursively();

SinglyLinkedList<Integer> originalList = reverser.getLabRatList(10);

System.out.println("Original List : " + originalList.toString());

originalList.start = reverser.reverse(originalList.start);

System.out.println("Reversed List : " + originalList.toString());

}

public Node<Integer> reverse(Node<Integer> list) {

if (list == null || list.next == null)

return list;

Node<Integer> nextItem = list.next;

list.next = null;

Node<Integer> reverseRest = reverse(nextItem);

nextItem.next = list;

return reverseRest;

}

private SinglyLinkedList<Integer> getLabRatList(int count) {

SinglyLinkedList<Integer> sampleList = new SinglyLinkedList<Integer>();

for (int i = 0; i < count; i++) {

sampleList.add(i);

}

return sampleList;

}

}

/*

* SAMPLE OUTPUT Original List : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Reversed List : 9,

* 8, 7, 6, 5, 4, 3, 2, 1, 0

*/

Java代码


package dsa.linkedlist;

/**

* This is a singly linked list with no prev pointer.

* @author Braga

* @param <E>

*/

public class SinglyLinkedList<E> {

Node<E> start;

int size;

public SinglyLinkedList(){

start = null;

size = 0;

}

//insertAtLast

public void add(E data){

insertAtLast(data);

}

public void insertAtLast(E data){

if(size==0){

start = new Node<E>();

start.next = null;

start.data = data;

}else{

Node<E> currentNode = getNodeAt(size-1);

Node<E> newNode = new Node<E>();

newNode.data = data;

newNode.next = null;

currentNode.next = newNode;

}

size++;

}

public void insertAtFirst(E data){

if(size==0){

start = new Node<E>();

start.next = null;

start.data = data;

}else{

Node<E> newNode = new Node<E>();

newNode.data = data;

newNode.next = start;

start = newNode;

}

size++;

}

public Node<E> getNodeAt(int nodePos) throws ArrayIndexOutOfBoundsException{

if(nodePos>=size || nodePos<0){

throw new ArrayIndexOutOfBoundsException();

}

Node<E> temp = start;//Move pointer to front

int counter = 0;

for(;counter<nodePos;counter++){

temp = temp.next;

}

return temp;

}

public void insertAt(int position, E data){

if(position == 0){

insertAtFirst(data);

}else if(position==size-1){

insertAtLast(data);

}else{

Node<E> tempNode = getNodeAt(position-1);

Node<E> newNode = new Node<E>();

newNode.data = data;

newNode.next = tempNode.next;

tempNode.next = newNode;

size++;

}

}

public Node<E> getFirst(){

return getNodeAt(0);

}

public Node<E> getLast(){

return getNodeAt(size-1);

}

public E removeAtFirst(){

if(size==0){

throw new ArrayIndexOutOfBoundsException();

}

E data = start.data;

start = start.next;

size--;

return data;

}

public E removeAtLast(){

if(size==0){

throw new ArrayIndexOutOfBoundsException();

}

Node<E> tempNode = getNodeAt(size-2);

E data = tempNode.next.data;

tempNode.next = null;

size--;

return data;

}

public E removeAt(int position){

if(position==0){

return removeAtFirst();

}else if(position == size-1){

return removeAtLast();

}else{

Node<E> tempNode = getNodeAt(position-1);

E data = tempNode.next.data;

tempNode.next = tempNode.next.next;

size--;

return data;

}

}

public int size(){

return size;

}

public String toString(){

if(size==0){

return "";

}else{

StringBuilder output = new StringBuilder();

Node<E> tempNode = start;

while(tempNode.next!=null){

output.append(tempNode.data).append(", ");

tempNode = tempNode.next;

}

output.append(tempNode.data);

return output.toString();

}

}

}

Java代码


　

　
package dsa.linkedlist;

public class Node<E>{
E data;
Node<E> next;
}

Java代码

package dsa.linkedlist;

public class ReverseLinkedListRecursively {

public static void main(String args[]) {
ReverseLinkedListRecursively reverser = new ReverseLinkedListRecursively();
SinglyLinkedList<Integer> originalList = reverser.getLabRatList(10);
System.out.println("Original List : " + originalList.toString());
originalList.start = reverser.reverse(originalList.start);
System.out.println("Reversed List : " + originalList.toString());
}

public Node<Integer> reverse(Node<Integer> list) {
if (list == null || list.next == null)
return list;
Node<Integer> nextItem = list.next;
list.next = null;
Node<Integer> reverseRest = reverse(nextItem);
nextItem.next = list;
return reverseRest;
}

private SinglyLinkedList<Integer> getLabRatList(int count) {
SinglyLinkedList<Integer> sampleList = new SinglyLinkedList<Integer>();
for (int i = 0; i < count; i++) {
sampleList.add(i);
}
return sampleList;
}
}
/*
* SAMPLE OUTPUT Original List : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Reversed List : 9,
* 8, 7, 6, 5, 4, 3, 2, 1, 0
*/

Java代码

package dsa.linkedlist;

/**
* This is a singly linked list with no prev pointer.
* @author Braga
* @param <E>
*/
public class SinglyLinkedList<E> {

Node<E> start;
int size;

public SinglyLinkedList(){
start = null;
size = 0;
}

//insertAtLast
public void add(E data){
insertAtLast(data);
}

public void insertAtLast(E data){
if(size==0){
start = new Node<E>();
start.next = null;
start.data = data;
}else{
Node<E> currentNode = getNodeAt(size-1);
Node<E> newNode = new Node<E>();
newNode.data = data;
newNode.next = null;
currentNode.next = newNode;
}
size++;
}

public void insertAtFirst(E data){
if(size==0){
start = new Node<E>();
start.next = null;
start.data = data;
}else{
Node<E> newNode = new Node<E>();
newNode.data = data;
newNode.next = start;
start = newNode;
}
size++;
}

public Node<E> getNodeAt(int nodePos) throws ArrayIndexOutOfBoundsException{
if(nodePos>=size || nodePos<0){
throw new ArrayIndexOutOfBoundsException();
}
Node<E> temp = start;//Move pointer to front
int counter = 0;
for(;counter<nodePos;counter++){
temp = temp.next;
}
return temp;
}

public void insertAt(int position, E data){
if(position == 0){
insertAtFirst(data);
}else if(position==size-1){
insertAtLast(data);
}else{
Node<E> tempNode = getNodeAt(position-1);
Node<E> newNode = new Node<E>();
newNode.data = data;
newNode.next = tempNode.next;
tempNode.next = newNode;
size++;
}
}

public Node<E> getFirst(){
return getNodeAt(0);
}

public Node<E> getLast(){
return getNodeAt(size-1);
}

public E removeAtFirst(){
if(size==0){
throw new ArrayIndexOutOfBoundsException();
}
E data = start.data;
start = start.next;
size--;
return data;
}

public E removeAtLast(){
if(size==0){
throw new ArrayIndexOutOfBoundsException();
}
Node<E> tempNode = getNodeAt(size-2);
E data = tempNode.next.data;
tempNode.next = null;
size--;
return data;
}

public E removeAt(int position){
if(position==0){
return removeAtFirst();
}else if(position == size-1){
return removeAtLast();
}else{
Node<E> tempNode = getNodeAt(position-1);
E data = tempNode.next.data;
tempNode.next = tempNode.next.next;
size--;
return data;
}
}

public int size(){
return size;
}

public String toString(){
if(size==0){
return "";
}else{
StringBuilder output = new StringBuilder();
Node<E> tempNode = start;
while(tempNode.next!=null){
output.append(tempNode.data).append(", ");
tempNode = tempNode.next;
}
output.append(tempNode.data);
return output.toString();
}
}

}