Array implements linked list (AcWing)

e[0]=1 e[1]=2 e[2]=3 e[3]=4 e[4]=5 e[5]=6

ne[0]=1 ne[1]=2 ne[2]=3 ne[3]=4 ne[4]=5 ne[5]=-1

Use ne to store the next subscript of e

initialization

We specify that -1 is set to an empty node

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

plug

First open up new nodes

e[idx]=x;

Then let the next node of the changed node point to the current first node (head)

ne[idx]=head;

Then disconnect the connection between head and the original first node, head points to the inserted node, and finally idx++;

head = idx;
idx++;

So the code for plugging in is:

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

Insert x after the element with subscript k

 

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

delete

 

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

topic:

AC code:

#include<iostream>
using namespace std;
const int N = 100010;
int head, e[N], ne[N], idx;

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

void add_to_head(int x)
{
	e[idx] = x;
	ne[idx] = head;
	head = idx;
	idx++;
}
//在下标为k的元素后面插入x
void add(int k, int x)
{
	e[idx] = x;
	ne[idx] = ne[k];
	ne[k] = idx;
	idx++;
}
//将下标为k的点后面的点删除掉
void move(int k)
{
	ne[k] = ne[ne[k]];
}

int main(void)
{
	int m;
	cin >> m;
	init();
	while (m--)
	{
		int k, x;
		char op;
		cin >> op;
		if (op == 'H')
		{
			cin >> x;
			add_to_head(x);
		}
		else if (op == 'D')
		{
			cin >> k;
			if (k == 0)
			{
				head = ne[head];
			}
			move(k - 1);
		}
		else
		{
			cin >> k >> x;
			add(k - 1, x);
		}
	}
	for (int i = head; i != -1; i = ne[i])
	{
		cout << e[i] << ' ';
	}
	return 0;
}