Given two linked lists sorted in increasing order. Merge them such a way that the result list is in decreasing order (reverse order).
Examples:
Input: a: 5->10->15->40 b: 2->3->20 Output: res: 40->20->15->10->5->3->2
Input: a: NULL b: 2->3->20 Output: res: 20->3->2
// https://www.geeksforgeeks.org/merge-two-sorted-linked-lists-such-that-merged-list-is-in-reverse-order/
#include <iostream>
#include <list>
using namespace std;
struct linked_list {
int data;
struct linked_list *next;
};
typedef struct linked_list node;
void print(node* n) {
while (n) {
cout<< n->data << "->";
n = n->next;
}
cout<< "NULL";
return;
}
node* insert (node* head, int n) {
node* list = new node;
list->data = n;
if (head == NULL) {
list->next = head;
head = list;
return head;
}
list->next = NULL;
node* last= head;
while (last->next != NULL )
last = last->next;
last->next = list;
return head;
}
node* push (node* head, int n) {
node* temp = new node;
temp->data = n;
temp->next = head;
head = temp;
return head;
}
node* reversemerge(node* head1, node* head2) {
node* head = NULL;
while (head1 && head2) {
if (head1->data <= head2->data) {
head=push(head,head1->data);
head1=head1->next;
}
else {
head=push (head, head2->data);
head2 = head2->next;
}
}
while (head1) {
head=push(head, head1->data);
head1=head1->next;
}
while (head2) {
head=push(head, head2->data);
head2=head2->next;
}
return head;
}
int main() {
int n;
node* head1 = NULL, *head2=NULL, *head3;
cout<< "Enter the first list: \n";
while (true) {
cout<< "Enter the elements, and -999 to stop: ";
cin>>n;
if (n==-9)
break;
else
head1=insert(head1,n);
}
cout<< "Enter the second list: \n";
while (true) {
cout<< "Enter the elements, and -999 to stop: ";
cin>>n;
if (n==-9)
break;
else
head2=insert(head2,n);
}
print(head1);
cout << "\n";
print(head2);
cout << "\n";
head3 = reversemerge(head1,head2);
print(head3);
}