单链表

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#include<iostream>
using namespace std;
const int N = 100010;
int e[N],ne[N],head,index; //e为value en存放下一个的index head为头结点 index为下标

//初始化链表
void init(){
    head = -1;
    index = 0;
}
//向链表头插入个节点
void add_to_head(int x){
    e[index] = x;
    ne[index] = head;
    head = index;
    index ++;
}
//删除第k个插入的数后面的数
void remove(int k){ 
    ne[k] = ne[ne[k]];
}
//在第k个数后面插入一个数
void add(int k , int x){
    e[index] = x;
    ne[index] = ne[k];
    ne[k] = index;
    index ++;

}
int main(){
    int m;
    cin >> m;
    init();
    while(m--){
        char op;
        cin >> op;

        if(op == 'H'){
            int x;
            cin >> x;
            add_to_head(x);
        } 
        else if(op == 'D'){
            int k;
            cin >> k;
            if (!k) head = ne[head];
            remove(k - 1);
        } else if(op == 'I'){
            int x,k;
            cin >> k >> x;
            add(k-1,x);
        }
    }
    for (int i = head ;i != -1; i = ne[i]) cout << e[i] << " ";




    return 0;
}