package com.coderising.week03.basic;
import java.util.NoSuchElementException;
import java.util.Stack;
import com.coding.basic.week01.Iterator;
import com.coding.basic.week01.List;
public class LinkedList implements List {
private Node head;
private int size;
public LinkedList() {
size = 0;
head = null;
}
public void add(Object o){
Node node = new Node(o);
if(head == null) {
head = node;
} else {
//p为游标 从头遍历到尾
Node p = head;
while(p.next != null) {
p = p.next;
}
p.next = node;
}
size++;
}
public void add(int index , Object o){
//判断链表不为空链表
if(head != null) {
Node p = head;
int k = 0;
//扫描单链表查找第index-1个节点
while(k < index-1 && p.next != null) {
k++;
p = p.next;
}
//判断是否找到第index-1个节点
if(p != null) {
Node node = new Node(o);
node.next = p.next;
p.next = node;
}
size++;
}
}
public Object get(int index){
if(index < 0 || index >= size) {
throw new IndexOutOfBoundsException();
} else {
Node p = head;
int k = 0;
while(k < index && p.next != null) {
k++;
p = p.next;
}
return p.data;
}
}
public Object remove(int index){
if(index < 0 || index >= size) {
throw new IndexOutOfBoundsException();
}
if(head == null) {
return null;
}
if(index == 0) {
head = head.next;
size--;
return head.data;
} else {
if(head != null) {
int k = 0;
Node p = head;
while(k < index -1 && p != null) {
k++;
p = p.next;
}
Node pn = p.next;
if(pn != null) {
p.next = pn.next;
size--;
return pn.data;
}
}
}
return null;
}
public int size(){
return size;
}
public void addFirst(Object o){
Node node = new Node(o);
node.next = head;
head = node;
size++;
}
public void addLast(Object o){
Node node = new Node(o);
if(head == null) {
head = node;
} else {
Node p = head;
while(p.next != null) {
p = p.next;
}
p.next = node;
}
size++;
}
public Object removeFirst(){
if(head == null) {
throw new NoSuchElementException();
}
Node node = head;
head = node.next;
size--;
return node.data;
}
public Object removeLast(){
if(head == null) {
throw new NoSuchElementException();
} else {
Node p = head;
int k = 0;
while(k < size-1 && p.next != null ) {
k++;
p = p.next;
}
Node last = p.next;
p.next = null;
size--;
return last.data;
}
}
public Iterator iterator(){
return null;
}
private static class Node{
Object data;
Node next;
private Node(Object o) {
this.data = o;
this.next = null;
}
}
/**
* 把该链表逆置
* 例如链表为 3->7->10 , 逆置后变为 10->7->3
*/
public void reverse(){
if(null == head || null == head.next) {
return;
}
Stack<Node> s = new Stack<Node>();
Node currentNode = head;
while(currentNode != null) {
s.push(currentNode);
Node nextNode = currentNode.next;
currentNode.next = null; //把链接断开
currentNode = nextNode;
}
head = s.pop();
currentNode = head;
while(!s.isEmpty()) {
Node nextNode = s.pop();
currentNode.next = nextNode;
currentNode = nextNode;
}
}
/**
* 删除一个单链表的前半部分
* 例如:list = 2->5->7->8 , 删除以后的值为 7->8
* 如果list = 2->5->7->8->10 ,删除以后的值为7,8,10
*/
public void removeFirstHalf(){
int num = size/2;
for(int i = 0; i < num; i++) {
removeFirst();
}
}
/**
* 从第i个元素开始, 删除length 个元素 , 注意i从0开始
* @param i
* @param length
*/
public void remove(int i, int length){
if(i < 0 || i >= size) {
throw new IndexOutOfBoundsException();
}
int len = size-i>=length ? length :size-i;
int k = 0;
while(k < len) {
remove(i);
k++;
}
}
/**
* 假定当前链表和list均包含已升序排列的整数
* 从当前链表中取出那些list所指定的元素
* 例如当前链表 = 11->101->201->301->401->501->601->701
* listB = 1->3->4->6
* 返回的结果应该是[101,301,401,601]
* @param list
*/
public int[] getElements(LinkedList list){
int[] arr = new int[list.size()];
for(int i = 0; i < list.size(); i++) {
arr[i] = (int) this.get((int) list.get(i));
}
return arr;
}
/**
* 已知链表中的元素以值递增有序排列,并以单链表作存储结构。
* 从当前链表中中删除在list中出现的元素
* @param list
*/
public void subtract(LinkedList list){
for (int i = 0; i < list.size(); i++) {
this.remove(list.get(i));
}
}
/**
* 传入数据删除节点
* @param obj
*/
public void remove(Object obj) {
if(head==null) {
throw new RuntimeException("LinkedList is empty!");
}
//如果要删除的节点是第一个,则把下一个节点赋值给第一个节点
if(head.data.equals(obj)){
head = head.next;
size--;
} else {
Node pre=head; //上一节点
Node cur=head.next; //当前节点
while(cur != null) {
if(cur.data.equals(obj)){
pre.next=cur.next;
size--;
}
pre=pre.next;
cur=cur.next;
}
}
}
/**
* 已知当前链表中的元素以值递增有序排列,并以单链表作存储结构。
* 删除表中所有值相同的多余元素(使得操作后的线性表中所有元素的值均不相同)
*/
public void removeDuplicateValues(){
if(head == null) {
throw new RuntimeException("LinkedList is empty!");
}
Node pre = head;
Node cur = head;
while(cur.next != null) {
cur = cur.next;
Object data = pre.data;
while(cur.data == data) {
if(cur.next == null) {
pre.next = null;
break;
}
pre.next = cur.next;
size--;
cur = cur.next;
if(cur == null) {
break;
}
}
pre = pre.next;
}
}
/**
* 已知链表中的元素以值递增有序排列,并以单链表作存储结构。
* 试写一高效的算法,删除表中所有值大于min且小于max的元素(若表中存在这样的元素)
* @param min
* @param max
*/
public void removeRange(int min, int max){
if(head == null) {
return;
}
Node node = head;
int start = -1;
int end = -1;
int i = 0;
while(node != null) {
if( (start == -1) && (int)node.data <= min) {
start = i;
}
if( (int)node.data >= max ) {
end = i;
break;
}
node = node.next;
i++;
}
if(start == -1) {
start = 0;
}
if(end == -1) {
end = size;
}
this.remove(start, end-start);
}
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.append("[");
Node node = head;
while (node != null) {
buffer.append(node.data);
if(node.next != null) {
buffer.append(",");
}
node = node.next;
}
buffer.append("]");
return buffer.toString();
}
/**
* 假设当前链表和参数list指定的链表均以元素依值递增有序排列(同一表中的元素值各不相同)
* 现要求生成新链表C,其元素为当前链表和list中元素的交集,且表C中的元素有依值递增有序排列
* @param list
*/
public LinkedList intersection( LinkedList list){
if(list == null) {
return null;
}
LinkedList result = new LinkedList();
int i1 = 0;
int i2 = 0;
while( i1 < this.size && i2 < list.size() ) {
int value1 = (int)this.get(i1);
int value2 = (int)list.get(i2);
if(value1 == value2) {
result.add(value1);
i1++;
i2++;
} else if (value1 < value2) {
i1++;
} else {
i2++;
}
}
return result;
}
}