USACO Section 2.2 Party Lamps

/*
ID: lucien23
PROG: lamps
LANG: C++
*/
/*
 * 此题的技巧之处就是需要注意到任何button只要按下2的倍数次就相当于没有按
 * 所以其实只需要考虑4个按钮，每个按钮是否被有效按下过一次就好
 * 直接使用枚举法，一共只有2^4=16种情况
 * 对于每种情况需要知道被按下的有效次数（也就是被按下过的按钮数），必须满足
 * (C-有效次数)%2=0才行，这样其他次数才能视为无效
 * 然后验证各种情况是否符合要求，将符合要求的情况按序输出即可
 */
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;

bool compPro(int *strNum1, int *strNum2)
{
	int i = 0;
	while (1)
	{
		if (strNum1[i] < strNum2[i])
			return true;
		else if (strNum1[i] > strNum2[i])
			return false;
		i++;
	}
}

int main()
{
	ifstream infile("lamps.in");
	ofstream outfile("lamps.out");
	if(!infile || !outfile)
	{
		cout << "file operation failure!" << endl;
		return -1;
	}

	int N, C;
	vector<int> vecOnLamps, vecOffLamps;
	vector<int*> results;
	infile >> N >> C;
	int num;
	infile >> num;
	while (num != -1)
	{
		vecOnLamps.push_back(num);
		infile >> num;
	}
	infile >> num;
	while (num != -1)
	{
		vecOffLamps.push_back(num);
		infile >> num;
	}
	int count = 0;
	for (int i=0; i<16; i++)
	{
		int *lamps = new int[N];
		for (int j=0; j<N; j++)
		{
			lamps[j] = 1;
		}

		int tempCnt = 0;
		for (int j=0; j<4; j++)
		{
			int temp = 1 << j;
			if ((temp & i) == temp)
				tempCnt++;
		}
		if (C < tempCnt || (C - tempCnt) % 2 != 0)
		{
			delete[] lamps;
			continue;
		}

		if (((1 << 0) & i) == (1 << 0))
		{
			for (int j=0; j<N; j++)
			{
				if (lamps[j] == 0)
					lamps[j] = 1;
				else
					lamps[j] = 0;
			}
		}

		if (((1 << 1) & i) == (1 << 1))
		{
			for (int j=0; j<N; j++)
			{
				if ((j+1)%2 == 1)
				{
					if (lamps[j] == 0)
						lamps[j] = 1;
					else
						lamps[j] = 0;
				}
			}
		}

		if (((1 << 2) & i) == (1 << 2))
		{
			for (int j=0; j<N; j++)
			{
				if ((j+1)%2 == 0)
				{
					if (lamps[j] == 0)
						lamps[j] = 1;
					else
						lamps[j] = 0;
				}
			}
		}

		if (((1 << 3) & i) == (1 << 3))
		{
			for (int j=0; j<N; j++)
			{
				if ((j+1)%3 == 1)
				{
					if (lamps[j] == 0)
						lamps[j] = 1;
					else
						lamps[j] = 0;
				}
			}
		}

		bool flag = true;
		for (vector<int>::iterator it=vecOnLamps.begin(); it!=vecOnLamps.end(); it++)
		{
			if (lamps[*it-1] != 1)
			{
				flag = false;
				break;
			}
		}

		if (!flag)
		{
			delete[] lamps;
			continue;
		}

		for (vector<int>::iterator it=vecOffLamps.begin(); it!=vecOffLamps.end(); it++)
		{
			if (lamps[*it-1] != 0)
			{
				flag = false;
				break;
			}
		}

		if (flag)
		{
			count++;
			results.push_back(lamps);
		} else {
			delete[] lamps;
		}
	}

	if (count == 0)
	{
		outfile << "IMPOSSIBLE" << endl;
	} else {
		sort(results.begin(), results.end(), compPro);
		for (int i=0; i<count; i++)
		{
			for (int j=0; j<N; j++)
			{
				outfile << results[i][j];
			}
			outfile << endl;
		}
	}

	return 0;
}