题解 | 【模板】链表

#include <iostream>
using namespace std;

class LinkNode {
  public:
    int val;
    LinkNode* next;
    LinkNode(int x): val(x), next(nullptr) {}
};

class LinkList {
  public:
    LinkNode* head;
    LinkList() {
        head = nullptr;
    }
    void insert(int x, int y) {
        LinkNode* tem = new LinkNode(y);
        if (head == nullptr) {
            head = tem;
            return;
        }
        LinkNode* pre = new LinkNode(0);
        pre->next = head;
        LinkNode* h = head;
        head = pre;
        while (h != nullptr) {
            if (h->val == x) {
                tem->next = h;
                pre->next = tem;
                head = head->next;
                return ;
            } else {
                pre = pre->next;
                h = h->next;
            }
        }
        pre->next=tem;
        head=head->next;
    }
    void Delete(int x) {
        LinkNode* pre = new LinkNode(0);
        pre->next = head;
        LinkNode* h = head;
        head = pre;
        while (h != nullptr) {
            if (h->val == x) {
                pre->next = h->next;
                head = head->next;
                return ;
            } else {
                h = h->next;
                pre = pre->next;
            }
        }
        head = head->next;
    }
};

int strToInt(string s) {
    int count = 0;
    int n = s.size();
    for (int i = 0; i < n; i++) {
        count = count * 10 + (s[i] - '0');
    }
    return count;
}

int main() {
    int n;
    cin >> n;
    getchar();
    LinkList l;
    for (int i = 0; i < n; i++) {
        string str;
        getline(cin, str);
        string s = str.substr(0, 7);
        if (s == "insert ") {
            string s1 = str.substr(7);
            int a = s1.find(' ');
            int x = strToInt(s1.substr(0, a));
            int y = strToInt(s1.substr(a + 1));
            l.insert(x, y);
        } else {
            string s1 = str.substr(7);            
            int x = strToInt(s1);
            l.Delete(x);
        }
    }
    if(l.head==nullptr)
    {
        cout<<"NULL"<<endl;
    }
    while(l.head!=nullptr)
    {
        cout<<l.head->val<<" ";
        l.head=l.head->next;
    }
    return 0;
}
// 64 位输出请用 printf("%lld")