Summat

input/code.cpp: In function 'int main()':
input/code.cpp:62:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (size_t i = 0; i < n*(n-1)/2; ++i) {
                     ~~^~~~~~~~~~~

#include <algorithm>
#include <iostream>
#include <vector>
#include <set>

using namespace std;

int n;
int b[5000];
int M[5000][100];
int c;
set<int> pivoted;

int find_pivot(int i) {
	for (int a = 0; a < c; ++a) {
		if (M[a][i] != 0 && pivoted.find(a) == pivoted.end()) {
			if (M[a][i] != 1) {
				int bs = M[a][i];
				for (int k = 0; k < n; ++k) {
					M[a][k] /= bs;
				}
				b[a] /= bs;
			}
			//cout << i << endl;
			//for (int k = 0; k < n; ++k) {
			//	cout << M[a][k] << " ";
			//}
			//cout << endl;
			pivoted.insert(a);
			return a;
		}
	}
	return -1;
}

void gauss() {
	for (int i = 0; i < n; ++i) {
		//for (int a = 0; a < c; ++a) {
		//for (int k = 0; k < n; ++k) {
		//	cout << M[a][k] << " ";
		//}
		//cout << b[a] << endl;
		//}
		int pivot = find_pivot(i);
		//cout << pivot << endl;
		if (pivot == -1) continue;
		for (int a = 0; a < c; ++a) {
			if (a != pivot && M[a][i] != 0) {
				int bs = M[a][i];
				for (int k = 0; k < n; ++k) {
					M[a][k] -= bs * M[pivot][k];
				}
				b[a] -= bs * b[pivot];
			}
		}
	}
}

int main()
{
	cin >> n;
	for (size_t i = 0; i < n*(n-1)/2; ++i) {
		cin >> b[i];
	}
	for (int i = 0; i < n; ++i) {
		for (int a = i + 1; a < n; ++a) {
			M[c][i] = 1;
			M[c][a] = 1;
			++c;
		}
	}
	gauss();
	for (auto x : pivoted) {
		cout << b[x];
		if (x != *pivoted.rbegin()) cout << " ";
	}
	cout << endl;
	//for (int i = 0; i < c; ++i) {
	//	for (int k = 0; k < n; ++k) {
	//		cout << M[i][k];
	//	}
	//	cout << endl;
	//	cout << b[i] << endl;
	//}
}

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 6

Group: 2, 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: WRONG ANSWER

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: WRONG ANSWER

Test 10

Group: 2, 3

Verdict: WRONG ANSWER

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: WRONG ANSWER

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: WRONG ANSWER

Test 15

Group: 3

Verdict: WRONG ANSWER