1.链表反向打印
1 public static void printNode(ListNode pHead){
2 /*
3 采用栈来从尾到头打印链表
4 Stack<Integer> stack=new Stack<>();
5 while (pHead !=null){
6 stack.push(pHead.val);
7 pHead=pHead.next;
8 }
9 while (!stack.isEmpty()){
10 System.out.println(stack.pop());
11 }*/
12 采用递归的形式打印
13 if(pHead !=null){
14 if(pHead.next !=null){
15 printNode(pHead.next);
16 }
17 System.out.println(pHead.val);
18 }
19 }
2.链表反转
1 public static ListNode reverseList(ListNode pHead){
2 ListNode preNode=null;
3 ListNode pNode=pHead;
4 ListNode res=null;
5 if(pHead==null){
6 return res;
7 }
8 while (pNode !=null){
9 ListNode nNode=pNode.next;
10 if (nNode == null) {
11 res=pNode;
12 }
13 pNode.next=preNode;
14 preNode=pNode;
15 pNode=nNode;
16 }
17 return res;
18 }
3.查找链表倒数第K个节点的值
1 public static int findKNode(ListNode pHead,int k){
2 ListNode fast=pHead; ListNode slow=pHead;
3 ListNode pNode=pHead;
4 if(pHead==null || k<=0){
5 return -1;
6 }
7 for(int i=0;i<k;i++){
8 if(fast.next !=null){ //用于判断k是否大于链表节点总数
9 fast=fast.next;
10 }else {
11 return -1;
12 }
13 }
14 while (fast !=null){
15 fast=fast.next;
16 slow=slow.next;
17 }
18 return slow.val;
19 }
4.判断链表是否成环
1 public static int findMiddleNode(ListNode pHead){
2 ListNode fast=pHead;
3 ListNode slow=pHead;
4 ListNode pNode=pHead;
5 if(pHead==null){
6 return -1;
7 }
8 while (fast.next !=null){
9 fast=fast.next.next;
10 slow=slow.next;
11 }
12 return slow.val;
13 }
5.合并两个排序的链表
1 public static ListNode mergeList(ListNode pHead1,ListNode pHead2){
2 if(pHead1==null){
3 return pHead2;
4 }
5 if (pHead2 == null) {
6 return pHead1;
7 }
8 ListNode res=null;
9 if(pHead1.val<pHead2.val){
10 res=pHead1;
11 res.next=mergeList(pHead1.next,pHead2);
12 }else {
13 res=pHead2;
14 res.next=mergeList(pHead1,pHead2.next);
15 }
16 return res;
17 }
