利用真值表法求取主析取范式以及主合取范式的实现(C++)

Posted 2021-12-03 Wecccccccc

代码如下:

#include <iostream>
#include <stack>
#include <string>
#include <vector>
using namespace std;
const int N = 300;
stack<char> s;
stack<char> v;
int seq;
bool vis[N];
bool flag[N];
void dfs(int n);
vector<int> ans_v;
vector<int> ans_vf;


void printMenu()
{
	cout << "代码其实有点不健壮，需要用括号来手动处理优先级!" << endl;
	cout << "比如:!!!(a&b&c)  要写成!(!(!(a&b&c)))" << endl;
	cout << "比如:!(a&b)->c 要写成 (!(a&b))>c" << endl;
	cout << "合取& 析取| 非! 条件> 双条件~ 括号() " << endl;
	cout << endl;
}

void printAns(vector<int> &ans_v, char f, char v)
{
	for (int i = 0; i < ans_v.size(); i++)
	{
		cout << f << ans_v[i];
		if (i != ans_v.size() - 1)
		{
			cout << v;
		}
	}
	cout << endl;
}




void calculator(int n, string &str)
{
	str = '(' + str + ')';
	for (int i = 0; i < str.length(); i++)
	{
		char tmp = str[i];

		if (tmp >= 'a' && tmp <= 'z')
		{
			vis[tmp - 'a'] = true;
			s.push(tmp);
		}
		else if (tmp == '(')
		{
			v.push(tmp);
		}
		else if (tmp == ')')
		{
			while (v.top() != '(')
			{
				s.push(v.top());
				v.pop();
			}
			v.pop();
		}
		else
		{
			v.push(tmp);
		}
	}




	stack<char>t;
	while (!s.empty())
	{
		t.push(s.top());
		s.pop();
	}
	s = t;


	stack<char>h(s);
	while (!h.empty())
	{
		cout << h.top();
		h.pop();
	}
	cout << endl;

	dfs(0);
	cout << "主合取范式为:" << endl;
	printAns(ans_v, 'm', '&');
	cout << "主析取范式为:" << endl;
	printAns(ans_vf, 'M', '|');


}




void dfs(int n)
{
	if (n == 26)
	{

		stack<char> s_s(s);
		stack<bool> s_t;
		while (!s_s.empty())
		{
			if (s_s.top() == '&' || s_s.top() == '|' || s_s.top() == '~' || s_s.top() == '>')
			{
				if (s_s.top() == '&')
				{
					s_s.pop();
					bool a2 = s_t.top();
					s_t.pop();
					bool a1 = s_t.top();
					s_t.pop();
					bool ans = a2 && a1;
					s_t.push(ans);
				}
				else if (s_s.top() == '|')
				{
					s_s.pop();
					bool a2 = s_t.top();
					s_t.pop();
					bool a1 = s_t.top();
					s_t.pop();
					bool ans = a2 || a1;
					s_t.push(ans);
				}
				else if (s_s.top() == '>')
				{
					s_s.pop();
					bool a2 = s_t.top();
					s_t.pop();
					bool a1 = s_t.top();
					s_t.pop();
					if (a1 == true && a2 == true)
					{
						s_t.push(true);
					}
					else if (a1 == true && a2 == false)
					{
						s_t.push(false);
					}
					else if (a1 == false)
					{
						s_t.push(true);
					}
				}
				else if (s_s.top() == '~')
				{
					s_s.pop();
					bool a2 = s_t.top();
					s_t.pop();
					bool a1 = s_t.top();
					s_t.pop();
					if (a1 == a2)
					{
						s_t.push(true);
					}
					else s_t.push(false);
				}
			}
			else if (s_s.top() == '!')
			{
				s_s.pop();
				bool tmp = !s_t.top();
				s_t.pop();
				s_t.push(tmp);
			}
			else
			{
				s_t.push(flag[s_s.top() - 'a']);
				s_s.pop();
			}

		}

		for (int i = 0; i < 26; i++)
		{
			if (vis[i])
			{
				cout << char(i + 'a') << "=" << flag[i] << " ";
			}
		}



		if (s_t.top())
		{

			ans_v.push_back(seq);
			cout << "ans=true" << endl;
		}
		else
		{
			ans_vf.push_back(seq);
			cout << "ans=false" << endl;
		}
		seq++;

		return;

	}

	if (vis[n])
	{
		for (int i = 0; i <= 1; i++)
		{
			flag[n] = i;
			dfs(n + 1);
		}
	}
	else
	{
		dfs(n + 1);
	}


}




int main()
{
	int n;
	string str;
	printMenu();
	cout << "请先输入式子含有的变量个数" << endl;
	cin >> n;
	cout << "按格式输入式子" << endl;
	cin >> str;
	calculator(n, str);
	return 0;
}

运行示例: