Lista

input/code.cpp: In function 'int main()':
input/code.cpp:31:6: warning: unused variable 'lastNum' [-Wunused-variable]
  int lastNum = 0;
      ^~~~~~~

#include <iostream>
#include <string>
#include <math.h>
#include <map>
#include <algorithm>
#include <vector>
#include <fstream>
#include <set>
#include <unordered_map>
#include <queue>
#include <climits>
#include <stack>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define LOOP(i,a,l) for (int i = a; i < l; i++)
#define LUO_VERKKO LOOP(i,0,m) {int a,b; cin >> a >> b; v[a].push_back(b); v[b].push_back(a);}
#define COLLECT for (int i = 0; i < n; i++) cin >> s[i]
#define PRINT_LIST(l) for (int i = 0; i < l.size(); i++) cout << l[i] << " "
#define S second
#define F first
#define A 999999999999999999LL
#define M 1000000007
//https://cses.fi/dt/
int n;
int t;
pair<int, int> d[11][11][5];
#define N (1<<17)
int main() {
	cin >> n;
	int lastNum = 0;
	vector<string> v;
	vector<string> t;
	for (int i = 0; i < n; i++)
	{
		string s; cin >> s;
		t.push_back(s);
	}
	string last = "999999999";
	for (int i = t.size()-1; i >= 0; i--)
	{
		string s = t[i];
		for (int j = s.length()-1; j >= 0; j--)
		{
			if (s[j] != '?') continue;
			string ch = string(1, last[j]);
			if (last[j] != '0') {
				s[j] = to_string(stoi(ch) - 1)[0];
				replace(s.begin(), s.end(), '?', '9');
			}
		}
		if (stoi(s) < stoi(last)) {
			v.push_back(s);
		}
		else {
			cout << "IMPOSSIBLE";
			exit(0);
		}
		last = s;
	}
	for (int i = v.size()-1; i >= 0; i--)
	{
		cout << v[i] << "\n";
	}
}

Test 1

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 2

Group: 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 3

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: RUNTIME ERROR

terminate called after throwing an instance of 'std::invalid_argument'
  what():  stoi

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 1, 2, 3

Verdict: ACCEPTED

Test 8

Group: 3

Verdict: WRONG ANSWER

Test 9

Group: 3

Verdict: WRONG ANSWER

Test 10

Group: 3

Verdict: WRONG ANSWER