[AcWing 827] 双链表

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点击查看代码

#include<iostream>

using namespace std;
const int N  = 1e5 + 10;
int e[N], r[N], l[N];
int idx;
void init()
{
    r[0] = 1;
    l[1] = 0;
    idx = 2;
}
void insert_lhead(int x)
{
    e[idx] = x;
    r[idx] = r[0];
    l[r[0]] = idx;
    l[idx] = 0;
    r[0] = idx;
    idx ++;
}
void insert_rhead(int x)
{
    e[idx] = x;
    l[idx] = l[1];
    r[l[1]] = idx;
    r[idx] = 1;
    l[1] = idx;
    idx ++;
}
void delete_k(int k)
{
    r[l[k]] = r[k];
    l[r[k]] = l[k];
}
void insert_r(int k, int x)
{
    e[idx] = x;
    r[idx] = r[k];
    l[r[k]] = idx;
    r[k] = idx;
    l[idx] = k;
    idx ++;
}
void insert_l(int k, int x)
{
    e[idx] = x;
    l[idx] = l[k];
    r[l[k]] = idx;
    l[k] = idx;
    r[idx] = k;
    idx ++;
}
int main()
{
    int m;
    scanf("%d", &m);
    init();
    while (m --) {
        string s;
        cin >> s;
        if (s == "L") {
            int x;
            cin >> x;
            insert_lhead(x);
        }
        if (s == "R") {
            int x;
            cin >> x;
            insert_rhead(x);
        }
        if (s == "D") {
            int k;
            cin >> k;
            delete_k(k + 1);
        }
        if (s == "IL") {
            int k, x;
            cin >> k >> x;
            insert_l(k + 1, x);
        }
        if (s == "IR") {
            int k, x;
            cin >> k >> x;
            insert_r(k + 1, x);
        }
    }
    for (int i = r[0]; i != 1; i = r[i])  printf("%d ", e[i]);
    return 0;
}

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1. 使用数组模拟双向链表；
2. 将 0 和 1 的位置置为链表的头结点和尾结点，便于操作；