Monistus

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n, q, m, a, b, c;
vector<pair<int,int>> v[202020];
int e[202020];
set<int> se;
string s;

class Node {
public:
    char data;
    Node* next;

    // Default constructor
    Node()
    {
        data = '0';
        next = NULL;
    }

    // Parameterised Constructor
    Node(char data)
    {
        this->data = data;
        this->next = NULL;
    }
};

class Linkedlist {

public:
    Node* head;
    // Default constructor
    Linkedlist() { head = NULL; }

    // Function to insert a
    // node at the end of the
    // linked list.
    void insertNode(int);

};

// Function to insert a new node. 
void Linkedlist::insertNode(int data) 
{ 
    // Create the new Node. 
    Node* newNode = new Node(data); 
  
    // Assign to head 
    if (head == NULL) { 
        head = newNode; 
        return; 
    } 
  
    // Traverse till end of list 
    Node* temp = head; 
    while (temp->next != NULL) { 
  
        // Update temp 
        temp = temp->next; 
    } 
  
    // Insert at the last. 
    temp->next = newNode; 
} 

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cin >> s;
	int pit=s.length();
	Node* beg = new Node(s[0]);
	Node* pbeg = beg;
	for (int i=1; i<pit; i++) {
		Node* nw = new Node(s[i]);
		pbeg->next=nw;
		pbeg=pbeg->next;
	}
	string alku="";
	Node* nod = beg;
	while(nod!=NULL) {
		if (nod->data<='9' && nod->data>='1') {
			int num=nod->data-'0';
			Linkedlist keski;
			Node* oldnod=nod;
			for (int i=0; i<num; i++) {
				nod=nod->next;
				keski.insertNode(nod->data);
			}
			oldnod=oldnod->next;
			Node *apu=keski.head;
			for (int i=1; i<num; i++) {
				apu=apu->next;
			}
			apu->next=oldnod;
			nod=keski.head;
		} else {
			alku+=nod->data;
			nod=nod->next;	
		}
	}
	/*while(i<pit) {
		if (s[i]<='9' && s[i]>='1') {
			int num = s[i]-'0';
			q=pit;
			string keski = s.substr(i+1,num);
			string loppu = s.substr(i+1+num,q-i-1);
			s=alku+keski+keski+loppu;
			pit+=num-1;
		} else {
			alku+=s[i];
			i++;
		}
	}*/
	cout << alku << "\n";
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: ACCEPTED

Test 6

Group: 1, 2

Verdict: ACCEPTED

Test 7

Group: 1, 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED