Gas tank

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

// Debug printing
#ifdef DEBUG
#define deb(fmt, args...) printf("DEBUG: %d: " fmt, __LINE__, ##args)
#define debug_print(fmt, args...) printf(fmt, ##args)
#else
#define deb(fmt, args...)
#define debug_print(fmt, args...)
#endif

void print_array(vector<int> in, const string title = "Vector")
{
	debug_print("DEBUG: %s [\nDEBUG: ", title.c_str());
	for (unsigned int i = 0; i < in.size(); i++) {
		debug_print("%d ", in[i]);
	}
	debug_print("\nDEBUG: ] END\n");
}

void print_matrix(vector<vector<int>> in, const string title = "Matrix")
{
	debug_print("DEBUG: %s [\nDEBUG: ", title.c_str());
	for (unsigned int i = 0; i < in.size(); i++) {
		for (unsigned int j = 0; j < in[i].size(); j++) {
			debug_print("%d ", in[i][j]);
		}
		debug_print("\nDEBUG: ");
	}
	debug_print("DEBUG: ] END\n");
}

int main(int argc, char *argv[])
{
	ios::sync_with_stdio(0);
	cin.tie(0);

	// Read the input parameters
	ll n;
	cin >> n;

	if ((n & 1) == 1) {
		// n is odd, we cannot ever reach it, make it even
		n--;
	}

	double err = 0.1;
	for (ll a = 1; a < 20; a++) {
		double b = 1.0 * a * a;
		ll c = -n;
		double res = (1.0 * -b + sqrt(b * b - 1.0 * 4 * a * c)) / (2 * a);
		double tmp = res;
		double rounded = round(res);
		// deb("a: %d, res: %f, tmp: %f, rounded: %f\n", a, res, tmp, round(res));
		if (abs(tmp - round(res)) <= err) {
			cout << a << " " << rounded << "\n";
			return 0;
		}
	}

	return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

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Test 6

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Test 10

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Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: ACCEPTED

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: ACCEPTED

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: WRONG ANSWER

Test 33

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Test 34

Verdict: ACCEPTED

Test 35

Verdict: WRONG ANSWER

Test 36

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Test 38

Verdict: ACCEPTED

Test 39

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Test 40

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Test 42

Verdict: ACCEPTED

Test 43

Verdict: WRONG ANSWER

Test 44

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Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: ACCEPTED

Test 48

Verdict: WRONG ANSWER

Test 49

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Test 50

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Test 68

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Test 79

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Test 80

Verdict: WRONG ANSWER