LeetCode——707，设计单链表
数据结构核心原理与算法应用
/**
* \* Created: liuhuichao
* \* Date: 2019/7/22
* \* Time: 28:48 PM
* \* Description: 设计链表
* \
* 设计链表的实现。您可以选择使用单链表或双链表。单链表中的节点应该具有两个属性：val 和 next。val 是当前节点的值，
* next 是指向下一个节点的指针/引用。如果要使用双向链表，则还需要一个属性 prev 以指示链表中的上一个节点。假设链表中的所有节点都是 0-index 的。
*
* 在链表类中实现这些功能：
*
* get(index)：获取链表中第 index 个节点的值。如果索引无效，则返回-1。
* addAtHead(val)：在链表的第一个元素之前添加一个值为 val 的节点。插入后，新节点将成为链表的第一个节点。
* addAtTail(val)：将值为 val 的节点追加到链表的最后一个元素。
* addAtIndex(index,val)：在链表中的第 index 个节点之前添加值为 val 的节点。如果 index 等于链表的长度，
* 则该节点将附加到链表的末尾。如果 index 大于链表长度，则不会插入节点。
* deleteAtIndex(index)：如果索引 index 有效，则删除链表中的第 index 个节点。
*
*
* 示例：
*
* MyLinkedList linkedList = new MyLinkedList();
* linkedList.addAtHead(1);
* linkedList.addAtTail(3);
* linkedList.addAtIndex(1,2); //链表变为1-> 2-> 3
* linkedList.get(1); //返回2
* linkedList.deleteAtIndex(1); //现在链表是1-> 3
* linkedList.get(1); //返回3
*
*
* 提示：
*
* 所有值都在 [1, 1000] 之内。
* 操作次数将在 [1, 1000] 之内。
* 请不要使用内置的 LinkedList 库。
*/
public class A707_DesignLinkedList {
class MyLinkedList {
Node head; //头部
int size; //长度
/**
* 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 < 0 || index >= size) {
return -1;
}
if (index == 0) {
return head.val;
}
Node cur = head;
while (index > 0) {
index--;
cur = cur.next;
}
return cur.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 newHead = new Node(val);
if (size == 0) {
head = newHead;
} else {
newHead.next = head;
this.head = newHead;
}
size++;
}
/**
* Append a node of value val to the last element of the linked list.
*/
public void addAtTail(int val) {
if (size == 0) {
return;
}
Node cur = head;
while (cur.next != null) {
cur = cur.next;
}
cur.next = new Node(val);
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;
}
Node cur = head;
if (index <= 0) {
addAtHead(val);
return;
}
if (index == size) {
addAtTail(val);
return;
}
while (index > 1) {
index--;
cur = cur.next;
}
Node newNode = new Node(val, cur.next);
cur.next = newNode;
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) {
return;
}
if (index == 0) {
head = head.next;
size--;
return;
}
Node cur = head;
while (index > 1) {
index--;
cur = cur.next;
}
if (cur.next.next == null) {
cur.next = null;
}
if (cur.next != null && cur.next.next != null) {
cur.next = cur.next.next;
}
size--;
}
/**
* console all data for debug
*
* @return
*/
public String consoleAll() {
StringBuilder result = new StringBuilder();
Node n = head;
result.append(n.val + ",");
while (n.next != null) {
n = n.next;
result.append(n.val + ",");
}
return result.toString();
}
}
class Node {
int val;
Node next;
Node(int val) {
this.val = val;
}
Node(int val, Node next) {
this.val = val;
this.next = next;
}
}
/**
* Your MyLinkedList object will be instantiated and called as such:
* MyLinkedList obj = new MyLinkedList();
* int param_1 = obj.get(index);
* obj.addAtHead(val);
* obj.addAtTail(val);
* obj.addAtIndex(index,val);
* obj.deleteAtIndex(index);
*/
@Test
public void test() {
//["MyLinkedList","addAtHead","addAtTail","addAtIndex","get","deleteAtIndex","get"]
//[[],[1],[3],[1,2],[1],[1],[1]]
/* MyLinkedList obj = new MyLinkedList();
obj.addAtHead(1);
obj.addAtTail(2);
obj.addAtIndex(1, 3);
int v1 = obj.get(1);
obj.deleteAtIndex(1);
int v2 = obj.get(1);
System.out.println(obj);*/
//["MyLinkedList","addAtHead","deleteAtIndex"]
//[[],[1],[0]]
/*MyLinkedList obj = new MyLinkedList();
obj.addAtHead(1);
obj.deleteAtIndex(0);*/
//["MyLinkedList","addAtHead","addAtTail","addAtIndex","get","deleteAtIndex","get"]
//[[],[1],[3],[1,2],[1],[0],[0]]
/* MyLinkedList obj = new MyLinkedList();
obj.addAtHead(1);
obj.addAtTail(3);
obj.addAtIndex(1, 2);
int v1 = obj.get(1);
obj.deleteAtIndex(0);
int v2 = obj.get(0);
System.out.println(obj);
*/
//["MyLinkedList","addAtIndex","get","deleteAtIndex"]
//[[],[-1,0],[0],[-1]]
//[null,null,0,null]
/* MyLinkedList obj = new MyLinkedList();
obj.addAtIndex(-1, 0);
int v1 = obj.get(0);
obj.deleteAtIndex(-1);*/
//["MyLinkedList","addAtHead[99]","addAtHead[11]","deleteAtIndex[2]","addAtTail[93]",
//[null,null,null,null,null,
MyLinkedList obj = new MyLinkedList();
obj.addAtHead(99);
obj.addAtHead(11);
obj.deleteAtIndex(2);
obj.addAtTail(93);
System.out.println(obj.consoleAll());
// "addAtIndex[1,51]","addAtTail[25]","addAtHead[82]","addAtTail[97]","addAtTail[45]",
//null,null,null,null,null,
obj.addAtIndex(1, 51);
obj.addAtTail(25);
obj.addAtHead(82);
obj.addAtTail(97);
obj.addAtTail(45);
System.out.println(obj.consoleAll());
// "addAtTail[43]","addAtHead[66]","addAtHead[0]","deleteAtIndex[9]","addAtHead[93]",
// null,null,null,null,null,
obj.addAtTail(43);
obj.addAtHead(66);
obj.addAtHead(0);
obj.deleteAtIndex(9);
obj.addAtHead(93);
System.out.println(obj.consoleAll());
// "get[3]","addAtHead[1]","addAtTail[33]","addAtIndex[3,82]","addAtIndex[4,36]",
// 82,null,null,null,null,
int v1 = obj.get(3);
obj.addAtHead(1);
obj.addAtTail(33);
obj.addAtIndex(3, 82);
obj.addAtIndex(5, 97);
System.out.println(obj.consoleAll());
// "get[8]","addAtHead[42]","addAtHead[16]","addAtHead[67]","addAtIndex[5,97]",
// 51,null,null,null,null,
int v2 = obj.get(8);
obj.addAtHead(42);
obj.addAtHead(16);
obj.addAtHead(67);
obj.addAtIndex(5, 97);
System.out.println(obj.consoleAll());
// "addAtTail[9]","get[19]","deleteAtIndex[12]","addAtTail[79]","addAtTail[43]",
// null,9,null,null,null,
obj.addAtTail(9);
int v3 = obj.get(19);
obj.deleteAtIndex(12);
obj.addAtTail(79);
obj.addAtTail(43);
System.out.println(obj.consoleAll());
// "addAtTail[96]","addAtTail[52]","get[3]","get[4]","addAtHead[46]",
// null,null,1,93,null,
obj.addAtTail(96);
obj.addAtTail(52);
int v4 = obj.get(3);
int v5 = obj.get(4);
obj.addAtHead(46);
System.out.println(obj.consoleAll());
// "addAtIndex[13,16]","addAtTail[32]","addAtTail[79]","addAtTail[28]","deleteAtIndex[20]",
// null,null,null,null,null,
obj.addAtIndex(13, 16);
obj.addAtTail(32);
obj.addAtTail(79);
obj.addAtTail(28);
obj.deleteAtIndex(20);
System.out.println(obj.consoleAll());
// "addAtIndex[10,70]","deleteAtIndex[27]","deleteAtIndex[14]","addAtHead[13]","addAtTail[81]",
// null,null,null,null,null,
obj.addAtIndex(10, 70);
obj.deleteAtIndex(27); //todo :这里有问题啊。。。
obj.deleteAtIndex(14);
obj.addAtHead(13);
obj.addAtTail(81);
System.out.println(obj.consoleAll());
// "addAtTail[69]","addAtTail[26]","deleteAtIndex[10]","addAtTail[57]","deleteAtIndex[6]",
// null,null,null,null,null,
obj.addAtTail(69);
obj.addAtTail(26);
obj.deleteAtIndex(10);
obj.addAtTail(57);
obj.deleteAtIndex(6);
System.out.println(obj.consoleAll());
// "addAtIndex[24,30]","addAtTail[89]","addAtTail[40]","addAtTail[14]","addAtIndex[23,92]",
// null,null,null,null,null,
obj.addAtIndex(24, 30);
obj.addAtTail(89);
obj.addAtTail(40);
obj.addAtTail(14);
obj.addAtIndex(23, 92);
System.out.println(obj.consoleAll());
// "deleteAtIndex[19]","addAtTail[14]","addAtHead[32]","addAtTail[19]","addAtTail[91]",
// null,null,null,null,null,
obj.deleteAtIndex(19);
obj.addAtTail(14);
System.out.println(obj.consoleAll());
obj.addAtHead(32);
obj.addAtTail(19);
obj.addAtTail(91);
System.out.println(obj.consoleAll());
// "addAtTail[8]","get[4]","addAtTail[57]","get[23]","get[36]",
// null,16,null,92,91,
obj.addAtTail(8);
int v6 = obj.get(4);
obj.addAtTail(57);
int v7 = obj.get(23);
System.out.println(obj.consoleAll());
int v8 = obj.get(36);
System.out.println(obj.consoleAll());
// "deleteAtIndex[24]","addAtTail[61]","addAtTail[62]","addAtHead[56]","addAtIndex[18,28]",
// null,null,null,null,null,
obj.deleteAtIndex(24);
obj.addAtTail(61);
obj.addAtTail(62);
obj.addAtHead(56);
obj.addAtIndex(18, 28);
System.out.println(obj.consoleAll());
// "deleteAtIndex[17]","addAtHead[15]","addAtTail[91]","addAtTail[54]","addAtHead[87]",
// null,null,null,null,null,
obj.deleteAtIndex(17);
obj.addAtHead(15);
obj.addAtTail(91);
obj.addAtTail(54);
obj.addAtHead(87);
System.out.println(obj.consoleAll());
// "addAtHead[70]","addAtIndex[14,66]","addAtIndex[36,60]","addAtHead[97]","addAtTail[12]",
// null,null,null,null,null,
obj.addAtHead(70);
obj.addAtIndex(14, 66);
obj.addAtIndex(36, 60);
obj.addAtHead(97);
obj.addAtTail(12);
System.out.println(obj.consoleAll());
// "addAtTail[13]","addAtTail[51]","addAtHead[45]","addAtHead[4]","addAtHead[98]",
// null,null,null,null,null,
obj.addAtTail(13);
obj.addAtTail(51);
obj.addAtHead(45);
obj.addAtHead(4);
obj.addAtHead(98);
System.out.println(obj.consoleAll());
// "addAtTail[57]","addAtIndex[1,12]","addAtTail[89]","addAtIndex[49,41]","get[17]",
// null,null,null,null,0,
obj.addAtTail(57);
obj.addAtIndex(1, 12);
obj.addAtTail(89);
obj.addAtIndex(49, 41);
int v9 = obj.get(17);
System.out.println(obj.consoleAll());
// "get[27]","addAtTail[0]","addAtIndex[17,6]","addAtHead[12]","addAtHead[87]",
// 97,null,null,null,null,
int v10 = obj.get(27);
obj.addAtTail(0);
obj.addAtIndex(17, 6);
obj.addAtHead(12);
obj.addAtHead(87);
System.out.println(obj.consoleAll());
// "addAtHead[78]","deleteAtIndex[5]","addAtHead[80]","addAtTail[34]","addAtHead[45]",
// null,null,null,null,null,
obj.addAtHead(78);
obj.deleteAtIndex(5);
obj.addAtHead(80);
obj.addAtTail(34);
obj.addAtHead(45);
System.out.println(obj.consoleAll());
// "addAtHead[7]","deleteAtIndex[58]"]
// null,null]
obj.addAtHead(7);
obj.deleteAtIndex(58);
System.out.println(obj.consoleAll());
System.out.println(obj);
}
}