移除和删除与向量中的条件匹配的指针

#include <iostream>

struct ListNode {
    int val;
    ListNode* next;
    ListNode(int x) : val(x), next(nullptr) {}
};

ListNode* removeElements(ListNode* head, int val) {
    // 创建一个虚拟头节点，简化头节点的处理
    ListNode* dummy = new ListNode(0);
    dummy->next = head;

    ListNode* current = dummy;
    while (current->next != nullptr) {
        if (current->next->val == val) {
            ListNode* temp = current->next;
            current->next = current->next->next;
            delete temp; // 释放内存
        } else {
            current = current->next;
        }
    }

    ListNode* newHead = dummy->next;
    delete dummy; // 释放虚拟头节点的内存
    return newHead;
}

// 辅助函数：打印链表
void printList(ListNode* head) {
    ListNode* current = head;
    while (current != nullptr) {
        std::cout << current->val << " ";
        current = current->next;
    }
    std::cout << std::endl;
}

int main() {
    // 创建链表 1 -> 2 -> 6 -> 3 -> 4 -> 5 -> 6
    ListNode* head = new ListNode(1);
    head->next = new ListNode(2);
    head->next->next = new ListNode(6);
    head->next->next->next = new ListNode(3);
    head->next->next->next->next = new ListNode(4);
    head->next->next->next->next->next = new ListNode(5);
    head->next->next->next->next->next->next = new ListNode(6);

    std::cout << "Original list: ";
    printList(head);

    int val = 6;
    head = removeElements(head, val);

    std::cout << "List after removing " << val << ": ";
    printList(head);

    return 0;
}