题解 | #从单向链表中删除指定值的节点#

import java.util.Scanner;

// 写得很罗嗦
public class Main {
    public static class ListNode {
        public int val;
        public ListNode next;
        public ListNode(int val) {
            this.val = val;
        }
        public ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public static ListNode insert(int pre, int fro, ListNode head) {
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        ListNode tmpPre = dummy;
        ListNode newNode = new ListNode(pre);
        while (tmpPre.next != null) {
            tmpPre = tmpPre.next;
            if (tmpPre.val == fro) {
                if (tmpPre.next != null) {
                    ListNode nextNode = tmpPre.next;
                    tmpPre.next = newNode;
                    newNode.next = nextNode;
                } else {
                    tmpPre.next = newNode;
                }
            }
        }
        return head;
    }

    public static ListNode delete(int val, ListNode head) {
        if (head == null) {
            return null;
        } else {
            ListNode dummy = new ListNode(-1);
            dummy.next = head;
            ListNode tmp = dummy;
            while (tmp.next != null) {
                if (tmp.next.val == val && tmp.next.next != null) {
                    tmp.next = tmp.next.next;
                }
                if (tmp.next.val == val && tmp.next.next == null) {
                    tmp.next = null;
                }
                tmp = tmp.next;
            }
        }
        return head;
    }
    

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextLine()) {
            String nextLine = in.nextLine();
            if (nextLine == null || nextLine == "") break;
            String[] com = nextLine.split(" "); 
            int len = Integer.parseInt(com[0]);
            int valHead = Integer.parseInt(com[1]);
            ListNode head = new ListNode(valHead);

            for (int i = 2; i < com.length - 1; i += 2) {
                int pre = Integer.parseInt(com[i]);
                int fro = Integer.parseInt(com[i + 1]);
                insert(pre, fro, head);
            }

            int delVal = Integer.parseInt(com[com.length - 1]);
            delete(delVal, head);
            while (head != null) {
                System.out.print(head.val + " ");
                head = head.next;
            }
        }
        
    }
}