Urkupillit

#include <iostream>
#include <string>
#include <math.h>
#include <map>
#include <algorithm>
#include <vector>
#include <fstream>
#include <set>
#include <unordered_map>
#include <queue>
#include <climits>
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 A 999999999999999999LL
//https://cses.fi/dt/
ll n;
int s[101010];
int main() {
	ll k;
	cin >> n >> k;
	for (int i = 0; i < n; i++)
	{
		s[i] = i+1;
	}
	int amount = 1;

	while ( ( k - (n - amount) ) >= 0) {
		if (amount - 1 <= n - amount) {
			int temp = s[amount - 1];
			s[amount - 1] = s[n - amount];
			s[n - amount] = temp;
		}
		k = k - (n - amount);
		amount++;
		if (k == 0) {
			k = n - amount;
			break;
		};
	}
	sort(s + (amount-1), s + n);
	swap(s[n-k-1], s[n - 1]);
	sort(s+n-k, s + n);
	
	for (int i = 0; i < n; i++)
	{
		cout << s[i] << " ";
	}
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED