力扣Java编译器_力扣--设计单链表
在鏈表類中實現這些功能:
get(index):獲取鏈表中第 index 個節點的值。如果索引無效,則返回-1。
addAtHead(val):在鏈表的第一個元素之前添加一個值為 val 的節點。插入后,新節點將成為鏈表的第一個節點。
addAtTail(val):將值為 val 的節點追加到鏈表的最后一個元素。
addAtIndex(index,val):在鏈表中的第 index 個節點之前添加值為 val 的節點。如果 index 等于鏈表的長度,則該節點將附加到鏈表的末尾。如果 index 大于鏈表長度,則不會插入節點。如果index小于0,則在頭部插入節點。
deleteAtIndex(index):如果索引 index 有效,則刪除鏈表中的第 index 個節點。
package com.lara.springbootconfig.algorithm;
/**
* @author lara
* @date 2020/3/20 17:05
*/
public class MyLinkedList {
private Node head;
private int size;
/**
* Initialize your data structure here.
*/
public MyLinkedList() {
}
/**
* Get the value of the index-th node in the linked list. If the index is invalid, return -1.
*/
public int get(int index) {
if (index > size - 1) {
return -1;
}
Node temp = head;
for (int i = 0; i < index; i++) {
temp = temp.next;
}
return temp.val;
}
/**
* Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list.
*/
public void addAtHead(int val) {
Node cur = new Node(val);
cur.next = head;
head = cur;
size++;
}
/**
* Append a node of value val to the last element of the linked list.
*/
public void addAtTail(int val) {
Node cur = new Node(val);
if (head == null) {
head = cur;
return;
}
Node temp = head;
while (null != temp.next) {
temp = temp.next;
}
temp.next = cur;
size++;
}
/**
* Add a node of value val before the index-th node in the linked list. If index equals to the length of linked list, the node will be appended to the end of linked list. If index is greater than the length, the node will not be inserted.
*/
public void addAtIndex(int index, int val) {
if (index > size) {
return;
}
if (index == 0) {
addAtHead(val);
size++;
return;
}
Node pre = head;
Node cur = pre.next;
for (int i = 1; i < index; i++) {
pre = pre.next;
cur = cur.next;
}
Node add = new Node(val);
add.next = cur;
pre.next = add;
size++;
}
/**
* Delete the index-th node in the linked list, if the index is valid.
*/
public void deleteAtIndex(int index) {
if (index >= 0 && index <= size - 1) {
if (index == 0) {
head = head.next;
size--;
return;
}
Node pre = head;
Node cur = pre.next;
for (int i = 1; i < index; i++) {
pre = pre.next;
cur = cur.next;
}
if (null == cur.next) {
pre.next = null;
} else {
pre.next = cur.next;
}
size--;
}
}
class Node {
private int val;
private Node next;
public Node(int val) {
this.val = val;
}
public int getVal() {
return val;
}
public void setVal(int val) {
this.val = val;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}
public void print() {
for (int i = 0; i < this.size; i++) {
System.out.print(this.get(i));
}
System.out.println("--------------");
}
public static void main(String[] args) {
MyLinkedList obj = new MyLinkedList();
obj.addAtHead(1);
obj.print();
obj.addAtTail(3);
obj.print();
obj.addAtIndex(1, 2);
obj.print();
obj.deleteAtIndex(1);
obj.print();
}
}
慢慢長路第一步,算法不能放棄!!!! 最好在力扣網提供的編輯器中自己手寫,嘗試下沒有編譯器看看自己還能不能寫代碼
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