题解 | 从单向链表中删除指定值的节点

#include <iostream>
using namespace std;

struct ListNode {
    int data;
    ListNode* next;
    // 构造函数，data(value), next(nullptr) 是初始化列表；
    ListNode(int value) : data(value), next(nullptr) {}
};

// 定义单向链表类
class SinglyLinkedList {
  private:
    ListNode* header;

  public:
    SinglyLinkedList(int val)  {
        header = new ListNode(val);
    }

    // 在 b 的后面插入 a
    void insertByElem(int a, int b) {
        ListNode* current = header;
        ListNode* newNode = new ListNode(a);

        while (current != nullptr && current->data != b) {
            current = current->next;
        }

        newNode->next = current->next;
        current->next = newNode;
    }

    // 遍历 链表
    void traverse() {
        ListNode* current = header;

        while (current != nullptr) {
            cout << current->data << " ";
            current = current->next;
        }
        cout << endl;
    }

    // 删除节点 val
    void deleteNode(int val) {
        ListNode* current = header;
        ListNode* prev = nullptr;

        while (current != nullptr && current->data != val) {
            prev = current;
            current = current->next;
        }

        // 没有 该节点
        if (current == nullptr)
            return;

        // 第一个就是 节点 val 所以 prev没有进入上面的循环
        if (prev == nullptr) {
            header = current->next;
        } else { // 节点 val 在链表中间；
            prev->next = current->next;
        }

        delete current;
    }

    // 析构函数
    ~SinglyLinkedList() {
        ListNode* current = header;
        ListNode* nextNode;
        while (current != nullptr) {
            nextNode = current->next;
            delete current;
            current = nextNode;
        }
    }
};

int main() {
    int n, head;

    while (cin >> n >> head) {
        SinglyLinkedList s(head);
        int a, b;
        while (--n) {
            cin >> a >> b;
            s.insertByElem(a, b);
        }

        int c;
        cin >> c;
        s.deleteNode(c);
        s.traverse();

    }


    return 0;
}