单链表

数组模拟链表可以加快速度，更利于优化算法

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

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

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

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

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

int main()
{
     int n; cin >> n;
    init();
    while (n--)
    {
        char c;int k,x;
      cin>>c;
        if (c == 'H')
        {
            scanf("%d",&x);
            add_head(x);
        }
        else if (c == 'I')
        {
            scanf("%d%d",&k,&x);
            insert(k-1, x);
        }
        else {
            
            scanf("%d",&k);
            if(k==0) head=ne[head];//注意这个特殊情况
            else{
            delete_link(k-1);}
        }
    }

    for (int i = head; i != -1; i = ne[i])
        printf("%d ",e[i]);
    return 0;
}

双链表

//注意事项：：：切记不要把下一位看成k+1，因为这是不对的空间是不连续的


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

void insert(int k,int x)
{
    e[idx] = x; 
    l[idx] = l[r[k]], r[idx] = r[k];
    l[r[k]] = idx; r[k] = idx++;
}

void del(int k)
{
    r[l[k]] = r[k];
    l[r[k]] = l[k];
}

int main()
{
    r[0] = 1; l[1] = 0; idx = 2;//用0表示开头，1表示结尾，不存实际值
    int n; cin >> n;
    while (n--)
    {
        int k, x; string c;
        cin >> c;
        if (c == "R")
        {
            cin >> x;
            insert(l[1], x);//结尾往左边插
        }
        else if (c == "L")
        {
            cin >> x;
            insert(0, x);//从0开始查
        }
        else if (c == "D")
        {
            cin >> k;
            del(k + 1);//查的是下标
        }
        else if (c == "IL")
        {
            cin >> k >> x;
            insert(l[k+1], x);
        }
        else {
            cin >> k >> x;
            insert(k + 1, x);
        }
    }
    for (int i = r[0]; i != 1; i = r[i])
    {
        cout << e[i] << " ";
    }
    return 0;
}

模拟栈

#include <iostream>

using namespace std;

const int N = 100010;

int m;
int stk[N], tt;

int main()
{
    cin >> m;
    while (m -- )
    {
        string op;
        int x;

        cin >> op;
        if (op == "push")
        {
            cin >> x;
            stk[ ++ tt] = x;
        }
        else if (op == "pop") tt -- ;
        else if (op == "empty") cout << (tt ? "NO" : "YES") << endl;//简化代码
        else cout << stk[tt] << endl;
    }

    return 0;
}

模拟队列

#include <iostream>

using namespace std;

const int N = 100010;

int m;
int q[N], hh, tt = -1;

int main()
{
    cin >> m;

    while (m -- )
    {
        string op;
        int x;

        cin >> op;
        if (op == "push")
        {
            cin >> x;
            q[ ++ tt] = x;
        }
        else if (op == "pop") hh ++ ;
        else if (op == "empty") cout << (hh <= tt ? "NO" : "YES") << endl;
        else cout << q[hh] << endl;
    }

    return 0;
}

单调栈

#include <iostream>

using namespace std;

const int N = 100010;

int stk[N], tt;

int main()
{
    int n;
    cin >> n;
    while (n -- )
    {
        int x;
        scanf("%d", &x);
        while (tt && stk[tt] >= x) tt -- ;//判断栈顶元素如果大于等于x,就弹出
        if (!tt) printf("-1 ");//如果空就输出-1
        else printf("%d ", stk[tt]);//没有就输出元素
        stk[ ++ tt] = x;//把新的加入
    }

    return 0;
}

//自写代码较为复杂，但精细
#include<iostream>
using namespace std;
const int N = 100010;
int a[N];
int main()
{
    int hh = -1;
    int n; cin >> n;
    while (n--)
    {
        int x; scanf("%d", &x);
        if (hh == -1)
        {
            printf("-1 ");
            a[++hh] = x;
         }
        else {
            if (a[hh] < x) {
                printf("%d ", a[hh]);
                a[++hh] = x;
            }
            else {
                while (a[hh] >= x && hh > -1) hh--;
                if (a[hh] < x&&hh!=-1)cout << a[hh] << " ";//一定加上hh!=-1的条件
                if(hh==-1)printf("-1 ");
                a[++hh] = x;
            }
        }
    }
    return 0;
}

单调队列

#include<iostream>
using namespace std;
const int N = 1000010;
int a[N],q[N]; int hh=0, tt=-1;
int main()
{
    int n, k; cin >> n >> k;
    for (int i = 0; i < n; i++) scanf("%d", &a[i]);
    for (int i = 0; i < n; i++)
    {
        if (hh <= tt && i - k + 1 > q[hh])hh++;//可以等于，相当于1个元素
        while (a[i] < a[q[tt]] && hh <= tt)tt--;
        q[++tt] = i;
        if (i-k+1>=0)cout << a[q[hh]] << " ";
    }
    cout<<endl;
    hh=0, tt=-1;
    for (int i = 0; i < n; i++)
    {
        if (hh <= tt && i - k + 1 > q[hh])hh++;
        while (a[i] >= a[q[tt]] && hh <= tt)tt--;
        q[++tt] = i;
        if (i-k+1>=0)cout << a[q[hh]] << " ";
    }
    return 0;
}