一、四向链表，输入n生成一个多维4向链表
java
@Data
static class ListNode<T>{
private T val;
ListNode<T> up,down,left,right;
public ListNode(T val){
this.val = val;
}
}
public static void main(String[] args){
ListNode<Integer> node = getResult(8);
ListNode<Integer> row = node;
while(row != null){
ListNode currNode = row;
while(currNode != null){
System.out.print(currNode.val + " ");
currNode = currNode.right;
}
System.out.println("");
row = row.down;
}
}
public static ListNode<Integer> getResult(int n){
if(n<=0){
return null;
}
ListNode<Integer> head = new ListNode<>(11);
head.left = null;
head.up = null;
ListNode<Integer> current = head;
for(int i = 2 ; i <= n ; i++){
ListNode<Integer> node = new ListNode<>(10 + i);
current.right = node;
node.left = current;
current = node;
}
ListNode<Integer> prevHead = head;
ListNode<Integer> rowCurrent = prevHead;
for(int row = 2 ; row <= n ; row++){
ListNode<Integer> rowHead = new ListNode<>(row * 10 + 1);
prevHead.down = rowHead;
rowHead.up = prevHead;
current = rowHead;
for(int col = 2; col <= n ; col++){
ListNode<Integer> node = new ListNode<>(row * 10 + col);
node.left = current;
current.right = node;
rowCurrent = rowCurrent.right;
rowCurrent.down = node;
node.up = rowCurrent;
current = node;
}
prevHead = rowHead;
rowCurrent = prevHead;
}
return head;
}二、输入树高，生成一个满二叉树。BinaryTree
java
static class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode parent;
public TreeNode(int val) {
this.val = val;
this.left = null;
this.right = null;
this.parent = null;
}
}
public static TreeNode generate(TreeNode parent,int depth) {
if (depth == 0) {
return null;
}
TreeNode node = new TreeNode(depth);
node.left = generate(node,depth - 1);
node.right = generate(node,depth - 1);
node.parent = parent;
return node;
}
public static void main(String[] args) {
TreeNode root = new TreeNode(1);
root = generate(root,3);
printTree(root);
}
public static void printTree(TreeNode root) {
if (root == null) {
return;
}
System.out.print(root.val + " ");
printTree(root.left);
printTree(root.right);
}其它方式参考：https://blog.csdn.net/wellsoonqmail/article/details/128262114
三、java实现双链表
java
static class ListNode{
private int val;//值
private ListNode prev;//前驱
private ListNode next;//后继
public ListNode(int val){
this.val=val;
}
}
public ListNode head;//双向链表的头节点
public ListNode last;//双向链表的尾节点
public void display(){
ListNode cur=head;
while(cur!=null){
System.out.print(cur.val+" ");
cur=cur.next;
}
System.out.println();
}
public int size(){
ListNode cur=head;
int count=0;
while(cur!=null){
count++;
cur=cur.next;
}
return count;
}
public void addFirst(int data) {
ListNode node = new ListNode(data);
//链表为空时
if (head == null) {
head = node;
last = node;
}
//有头指针，不为空
else {
node.next = head;
head.prev = node;
head = node;
}
}
public void addLast(int data){
ListNode node=new ListNode(data);
//当链表为空
if(head==null){
head=node;
last=node;
}
//有头指针，不为空
else{
last.next=node;
node.prev=last;
last=last.next;
}
}
//删除第一次出现关键字key的节点，一共三种情况
public void remove(int key){
ListNode cur = head;
while (cur != null) {
if(cur.val == key) {
//1.当删除头节点
if(cur == head) {
head = head.next;
//1.1当头指针不为空时
if(head != null) {
//考虑只有一个节点的情况下
head.prev = null;
}else {
//1.2头指针为空时
last = null;
}
}else {
//2.删除中间节点 和 3.尾巴节点
if(cur.next != null) {
//删除中间节点
cur.prev.next = cur.next;
cur.next.prev = cur.prev;
}else {
//尾巴节点
cur.prev.next = cur.next;
last = last.prev;
}
}
return;
}else {
cur = cur.next;
}
}
}参照：https://blog.csdn.net/m0_63732435/article/details/127195219
四、假设有n个面试官，每个面试者预约的时间是[ai， bi]（包括边界），1号面试官在bi时刻结束后，至多能继续bi+1时刻开始的面试，请帮忙计算1号面试官至多能面试多少个面试者。//贪婪策略：每次选择最早结束的活动
java
private static int [][] times = {{1,3},{1,4},{3,5},{4,5}};
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
Arrays.sort(times, (o1, o2) -> {
if(o1[1] == o2[1]){
return o1[0] - o2[0];
}else{
return o1[1] - o2[1];
}
});
int res = 1;
int end = times[0][1];
for(int i = 1; i < n; i++){
if(times[i][0] > end){
end = times[i][1];
res++;
}
}
System.out.println(res);
}参照：https://blog.csdn.net/qq_45908682/article/details/124661279
贪婪算法：https://blog.csdn.net/TuttuYYDS/article/details/124636914