如何更改链表中的元素？

#include <iostream>

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

void changeLinkedList(ListNode* head, int oldValue, int newValue) {
    ListNode* curr = head;
    while (curr != nullptr) {
        if (curr->val == oldValue) {
            curr->val = newValue;
            break;
        }
        curr = curr->next;
    }
}

int main() {
    // 创建链表
    ListNode* head = new ListNode(1);
    ListNode* node2 = new ListNode(2);
    ListNode* node3 = new ListNode(3);
    head->next = node2;
    node2->next = node3;

    // 打印修改前的链表
    ListNode* curr = head;
    while (curr != nullptr) {
        std::cout << curr->val << " ";
        curr = curr->next;
    }
    std::cout << std::endl;

    // 修改链表中的元素
    changeLinkedList(head, 2, 4);

    // 打印修改后的链表
    curr = head;
    while (curr != nullptr) {
        std::cout << curr->val << " ";
        curr = curr->next;
    }
    std::cout << std::endl;

    // 释放链表内存
    delete head;
    delete node2;
    delete node3;

    return 0;
}