刪除鏈表中一個位於中間位置的節點

Problem

Delete a node in the middle of list, given only access list once

Solution

#include <iostream>

using namespace std;

typedef struct linked_list{
    int data;
    struct linked_list *next;
}Linked_list;

int add_node(Linked_list **head, int d)
{
    Linked_list *l = new Linked_list;
    if(l == NULL) return 0;
    Linked_list *t = *head;
    l->data = d;
    l->next = NULL;

    if(*head == NULL){
        *head = l;
        return 1;
    }

    while(t->next != NULL){
        t = t->next;
    }

    t->next = l;

    return 1;
}

void del_mid_elem(Linked_list *head, Linked_list *l)
{
    Linked_list *t;

    if(head->next == NULL && head->next == NULL){
        return;
    }

    t = l->next;
    l->data = l->next->data;
    l->next = l->next->next;

    delete t;
}

void delete_list(Linked_list *head)
{
    while(head != NULL){
        Linked_list *t = head->next;
        delete head;
        head = t;
    }
}

int main(int argc, char* argv[])
{
    Linked_list *head = NULL;
    Linked_list *l;

    add_node(&head, 1);
    add_node(&head, 1);
    add_node(&head, 2);
    add_node(&head, 3);
    add_node(&head, 9);
    add_node(&head, 4);
    add_node(&head, 1);
    add_node(&head, 5);

    cout << "before" << endl;
    l = head;
    while(l!=NULL){
        cout << l->data << endl;
        l = l->next;
    }

    l = head;
    while(l!=NULL){
        if(l->data == 9) break;;
        l = l->next;
    }

    cout << "after deleting " << l->data << endl;

    del_mid_elem(head, l);

    l = head;
    while(l!=NULL){
        cout << l->data << endl;
        l = l->next;
    }

    delete_list(head);

    return 0;
}

Output

before
1
1
2
3
9
4
1
5
last 0 in the list
last 1 in the list
5
last 2 in the list
1
5