题解 | #从单向链表中删除指定值的节点#

import java.util.Scanner;
import java.util.Arrays;
import java.lang.String;
class ListNode{
    int val;
    ListNode next;
    ListNode(){}
    ListNode(int val){
        this.val = val;
    }
    ListNode(int val, ListNode next){
        this.next = next;
    }
    
    public static ListNode arrayToListNode(int[] array){
        int length = array.length;
        ListNode root = new ListNode(array[0]);
        ListNode pre = root;
        for(int i = 1; i < array.length; i++){
            pre.next = new ListNode(array[i]);
            pre = pre.next;
        }
        return root;
    }
    
    public static void print(ListNode node){
        if(node == null) System.out.print(node);
        while(node != null){
            System.out.print(node.val);
            node = node.next;
        }
        System.out.println();
    }
    
    public static void printOrSpace(ListNode node){
        if(node == null) System.out.print(node);
        while(node != null){
            System.out.print(node.val);
            node = node.next;
            if(node != null){
                System.out.print(" ");
            }
        }
        System.out.println();
    }
}
public class Main{
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNext()){
            String value = scanner.nextLine();
            value = value.trim();
            ListNode node = getNode(value);
            ListNode.printOrSpace(node);
        }
    }
    
    public static ListNode getNode(String valueKey){
        ListNode node = new ListNode(-1);
        
        //计数器
        int count = 0;
        //待插入的节点值
        int value = -1;
        //插入位置（元素尾部）
        int num = 0;
        StringBuilder builder = new StringBuilder();
        
        int headCount = 0;
        for(int i = 0; i < valueKey.length(); i++){
            if(valueKey.charAt(i) != ' '){
                int singleNumber = valueKey.charAt(i) - '0';
                builder.append(singleNumber);
                if(i == valueKey.length() - 1){
                    num = Integer.valueOf(builder.toString());
//                     System.out.println("delete:"+num);
                    //删除节点
                    node = removeNode(node,num);
                } 
            } else {
                
                if(builder != null){
                    num = Integer.valueOf(builder.toString());
                    builder.setLength(0);
                   if(headCount == 1){
                       //创建头结点
                       node = new ListNode(num);
                   } 
                   if(headCount >= 2) {
                       count++;
                       if(count == 2){
                       node = insertNode(node,num,value);
                       count = 0;
                       value = -1;
                       } else {
                           value = num;
                       }
                   }
                   headCount++;
                }
            }
            
        }
        return node;
    }
    
    public static ListNode insertNode(ListNode node,int insertNodeValue, int newNodeValue){
        ListNode cur = node;
        ListNode newNode = new ListNode(newNodeValue);
        while(cur != null){
            if(cur.val == insertNodeValue){
                ListNode curNext = cur.next;
                cur.next = newNode;
                newNode.next = curNext;
            } 
            cur = cur.next;
        }
        return node;
    }
    
    ///链表删除某个节点
    public static ListNode removeNode(ListNode node,int deleteVal){
        //临时头结点
        ListNode temp = new ListNode(-1);
        temp.next = node;
        //当前节点的上一个节点
        ListNode pre = temp;
        //当前节点
        ListNode cur = node;
        
        while(cur != null){
            if(cur.val == deleteVal){
                pre.next = cur.next;
            } else {
                pre = cur;
            }
            cur = cur.next;
        }
        return temp.next;
    }
    
    
}