【牛客网 - 华为机试】HJ48 从单链表中删除指定值的节点
题目描述
输入一个单向链表和一个节点的值,从单向链表中删除等于该值的节点,删除后如果链表中无节点则返回空指针。
链表的值不能重复。
构造过程,例如
1 <- 2
3 <- 2
5 <- 1
4 <- 5
7 <- 2
最后的链表的顺序为 2 7 3 1 5 4
删除 结点 2
则结果为 7 3 1 5 4
链表长度不大于1000,每个节点的值不大于10000。
本题含有多组样例。
输入描述:
1 输入链表结点个数
2 输入头结点的值
3 按照格式插入各个结点
4 输入要删除的结点的值
输出描述:
输出删除结点后的序列,每个数后都要加空格
示例1
输入
5
2
3 2
4 3
5 2
1 4
3
输出
2 5 4 1
解题思路
package 笔试汇总.华为;/**
* Copyright (C), 2019-2021
* author candy_chen
* date 2021/4/18 17:21
*
* @Classname HJ48
* Description: 从单链表中删除指定值的节点
*/
import java.util.Scanner;
/**
*
*/
public class HJ48 {
private ListNode head;
private static class ListNode {
int val;
ListNode next;
ListNode(int val) {
this.val = val;
}
ListNode(int val, ListNode next) {
this.val = val;
this.next = next;
}
}
public HJ48(int val) {
head = new ListNode(val);
}
public void insert(int val,int node){
ListNode p = head;
while (p.val != node){
p = p.next;
}
p.next = new ListNode(val, p.next);
}
public void delete(int node){
ListNode dummy = new ListNode(0, head);
ListNode p = dummy;
while (p.next != null && p.next.val != node){
p = p.next;
}
if (p.next != null){
p.next = p.next.next;
}
head = dummy.next;
}
public ListNode head(){
return this.head;
}
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
while (in.hasNext()) {
int n = Integer.parseInt(in.next());
int val = Integer.parseInt(in.next());
HJ48 solution = new HJ48(val);
for (int i = 1; i < n; i++) {
val = Integer.parseInt(in.next());
int node = Integer.parseInt(in.next());
solution.insert(val, node);
}
val = Integer.parseInt(in.next());
solution.delete(val);
ListNode p = solution.head();
while (p != null) {
System.out.print(p.val + " ");
p = p.next;
}
System.out.println();
}
}
}
优秀的代码——简洁,复杂度低
import java.io.*;
public class Main {
//构建节点
public static class Node {
Node next;
int val;
Node(int val) {
this.val = val;
next = null;
}
}
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String str = null;
while ((str = br.readLine()) != null) {
if (str.equals("")) continue;
String[] params = str.split(" ");//str.split(" ")将字符串按空格分开并返回为字符串数组的形式
int n = Integer.parseInt(params[0]);
Node head = new Node(Integer.parseInt(params[1]));//将字符串数字默认转换为整型的十进制数,使用的是Integer类
for (int i = 1; i < n; i++) {
int pre = Integer.parseInt(params[2*i+1]), nxt = Integer.parseInt(params[2*i]);
Node temp = head;
while (temp.val != pre) temp = temp.next;//遍历插入点的位置
Node node = new Node(nxt);
node.next = temp.next;
temp.next = node;
}
int del = Integer.parseInt(params[2*n]);
StringBuilder ans = new StringBuilder();//StringBuilder类可以更改字符串,不会占用多余的空间,始终是一个数组
Node temp = head;
while (temp != null) {
if (temp.val != del) ans.append(temp.val).append(" ");//append为StringBuilder类中添加字符串的方法
temp = temp.next;
}
// 注意要求每个数后面都加空格
System.out.println(ans.toString());//转换为字符串格式
}
}
}