• 单链表中最常用的是邻接表
• 邻接表就是n个单链表
• 邻接表最主要的用途就是存储树与图
• 这里主要用数组来模拟链表，也叫静态链表

模板一

• 注意，这里面的k - 1代表第k个插入的元素，因为idx是从0开始的
• C++

// head存储链表头，e[]存储节点的值，ne[]存储节点的next指针，idx表示当前用到了哪个节点
int head, e[N], ne[N], idx;

// 初始化
void init()
{
    head = -1;
    idx = 0;
}

// 在链表头插入一个数a
void insert_to_head(int a)
{
    e[idx] = a, ne[idx] = head, head = idx ++ ;
}

// 将a插到下标是k的节点后面
void insert(int k, int a)
{
    e[idx] = a;
    ne[idx] = ne[k];
    ne[k] = idx ++;
}

// 将头结点删除，需要保证头结点存在
void remove_head()
{
    head = ne[head];
}

// 将下标是k的节点后面的节点删掉
void remove(int k) {
    ne[k] = ne[ne[k]];
}

// 遍历链表
for (int i = head; i != -1; i = ne[i]) {
    cout << e[i] << ' ';
}

• Java

public static int head, idx;
public static int[] e = new int[N];
public static int[] ne = new int[N];

public static void init() {
    head = -1;
    idx = 0;
}

public static void insert_to_head(int a) {
    e[idx] = a;
    ne[idx] = head;
    head = idx++;
}

public static void insert(int k, int a) {
    e[idx] = a;
    ne[idx] = ne[k];
    ne[k] = idx++;
}

public static void remove_head() {
    head = ne[head];
}

public static void remove(int k) {
    ne[k] = ne[ne[k]]
}

for (int i = head; i != -1; i = ne[i]) {
    pw.print(e[i] + " ");
}

模板二

• 改良版：将head存入ne[0]中，这样可以将添加和删除方法进行优化
• 注意：改良版中的k指的是第k个加入链表中的元素
• C++

int e[N], ne[N], idx;

void init()
{
    head = -1;
    idx = 0;
}

void insert_to_head(int a)
{
    e[idx] = a;
    ne[idx] = head;
    head = idx ++;
}

void insert(int k, int a)
{
    e[idx] = a;
    ne[idx] = ne[k];
    ne[k] = idx ++;
}

void remove_head()
{
    head = ne[head];
}

void remove(int k) {
    ne[k] = ne[ne[k]];
}

for (int i = head; i != -1; i = ne[i]) {
    cout << e[i] << ' ';
}

• Java

public static int idx;
public static int[] e = new int[N];
public static int[] ne = new int[N];

public static void init() {
    ne[0] = -1;
    idx = 1;
}

public static void insert(int k, int a) {
    e[idx] = a;
    ne[idx] = ne[k];
    ne[k] = idx++;
}

public static void insert_to_head(int a) {
    insert(0, a);
}

public static void remove(int k) {
    ne[k] = ne[ne[k]]
}

public static void remove_head() {
    remove(0);
}

for (int i = head; i != -1; i = ne[i]) {
    pw.print(e[i] + " ");
}

练习

01 单链表

• 题目

• 题解
• 模板一

import java.io.*;

public class Main {
    public static final int N = 100010;
    public static int M;
    public static int head = -1;
    public static int idx = 0;
    public static int[] e = new int[N];
    public static int[] ne = new int[N];

    public static void insert_to_head(int x) {
        e[idx] = x;
        ne[idx] = head;
        head = idx++;
    }

    public static void insert(int k, int x) {
        e[idx] = x;
        ne[idx] = ne[k];
        ne[k] = idx++;
    }

    public static void remove_head() {
        head = ne[head];
    }

    public static void remove(int k) {
        ne[k] = ne[ne[k]];
    }


    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        M = Integer.parseInt(br.readLine());

        while (M-- > 0) {
            String[] str1 = br.readLine().split(" ");
            if (str1[0].equals("H")) {
                insert_to_head(Integer.parseInt(str1[1]));
            } else if (str1[0].equals("I")) {
                insert(Integer.parseInt(str1[1]) - 1, Integer.parseInt(str1[2]));
            } else {
                int k = Integer.parseInt(str1[1]);
                if (k == 0) {
                    remove_head();
                } else {
                    remove(k - 1);
                }
            }
        }

        for (int i = head; i != -1; i = ne[i]) {
            pw.print(e[i] + " ");
        }

        pw.close();
        br.close();
    }
}

• 模板二

import java.io.*;

public class Main {
    public static final int N = 100010;
    public static int M;
    public static int[] e = new int[N];
    public static int[] ne = new int[N];
    public static int idx;

    public static void init() {
        idx = 1;
        ne[0] = -1;
    }

    public static void insert(int k, int x) {
        e[idx] = x;
        ne[idx] = ne[k];
        ne[k] = idx++;
    }

    public static void remove(int k) {
        ne[k] = ne[ne[k]];
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

        M = Integer.parseInt(br.readLine());
        init();
        while (M-- > 0) {
            String[] str1 = br.readLine().split(" ");
            if (str1[0].equals("H")) {
                insert(0, Integer.parseInt(str1[1]));
            } else if (str1[0].equals("I")) {
                insert(Integer.parseInt(str1[1]), Integer.parseInt(str1[2]));
            } else {
                remove(Integer.parseInt(str1[1]));
            }
        }

        for (int i = ne[0]; i != -1; i = ne[i]) {
            pw.print(e[i] + " ");
        }
        pw.close();
        br.close();
    }
}