Cod sursa(job #2640835)

Utilizator mirceamaierean41Mircea Maierean mirceamaierean41 Data 8 august 2020 15:51:56
Problema Semne Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.36 kb
#include <fstream>

class InParser
{
#pragma warning(disable:4996)
private:
	FILE* fin;
	char* buff;
	int sp;
	char read()
	{
		++sp;
		if (sp == 4096)
		{
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}
public:
	InParser(const char* nume)
	{
		sp = 4095;
		buff = new char[4096];
		fin = fopen(nume, "r");
	}
	InParser& operator >> (int& n)
	{
		char c;
		while (!isdigit(c = read()));
		n = c - '0';
		while (isdigit(c = read()))
			n = n * 10 + c - '0';
		return *this;
	}
	InParser& operator >> (long long& n)
	{
		int sgn = 1;
		char c;
		while (!isdigit(c = read()) && c != '-');
		if (c == '-')
			sgn = -1;
		else
			n = c - '0';
		while (isdigit(c = read()))
			n = n * 10 + c - '0';
		n *= sgn;
		return *this;
	}
};

InParser fin("semne.in");
std::ofstream fout("semne.out");

const int NMAX = 5 * 1e4 + 1;

char sgn[NMAX];

int n;
long long a[NMAX], _s, s;

bool solve(long long sum, int n)
{
	if (sum < s)
		return false;
	if (sum == s)
		return true;
	for (int i = n; i >= 0; --i)
	{
		sgn[i] = '-';
		if (solve(sum - 2 * a[i], i - 1))
			return true;
		sgn[i] = '+';
	}
	return false;
}

int main()
{
	fin >> n >> s;
	for (int i = 0; i < n; ++i)
	{
		fin >> a[i];
		_s += a[i];
		sgn[i] = '+';
	}

	solve(_s, n - 1);

	fout << sgn << "\n";

	fout.close();
	return 0;
}