Monistus

input/code.cpp: In function 'bool isClear(std::string)':
input/code.cpp:10:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   10 |         for(int i=0;i<s.size();i++){
      |                     ~^~~~~~~~~
input/code.cpp: In function 'void dfs(std::string)':
input/code.cpp:21:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |         for(int i=0;i<s.size();i++){
      |                     ~^~~~~~~~~
input/code.cpp:25:36: warning: comparison of integer expressions of different signedness: 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   25 |                         if(t.size()<m){
      |                            ~~~~~~~~^~

#include<bits/stdc++.h>
using namespace std;
string str,str2;

bool isDigit(char c){
	return c>='0'&&c<='9';
}

bool isClear(string s){
	for(int i=0;i<s.size();i++){
		if(isDigit(s[i]))return false;
	}
	return true;
}

void dfs(string s){
	if(s.size()==1){
		str2+=s;
		return;
	}
	for(int i=0;i<s.size();i++){
		if(isDigit(s[i])){
			int m=s[i]-'0';
			string t=s.substr(i+1,m);
			if(t.size()<m){
				dfs(s.substr(i,m));
			}
			dfs(t);
		}
		else{
			dfs(s.substr(i,1));
		}
	}
}
int main(){
	cin>>str;
	while(!isClear(str)){
		dfs(str);
		str=str2;
		str2="";
	}
	cout<<str<<endl;
	return 0;
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: RUNTIME ERROR

Test 4

Group: 1, 2

Verdict: ACCEPTED

Test 5

Group: 1, 2

Verdict: RUNTIME ERROR

Test 6

Group: 1, 2

Verdict: RUNTIME ERROR

Test 7

Group: 1, 2

Verdict: RUNTIME ERROR

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: RUNTIME ERROR

Test 10

Group: 2

Verdict: RUNTIME ERROR

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED