HexadecimalCalculation381.cpp

#include <iostream>
#include <cstring>
#include <stack>
#include <iomanip>
using namespace std;

int main() {
	char str[101];
	while (cin >> str) {
		char postfix[101];
		stack <int>result;
		int sum;
		int j = 0;
		stack <char>s;
		for (int i = 0; str[i] != '\0'; i++) {
			if (str[i] == ' ')
				continue;
			if ((str[i] >= '0'&&str[i] <= '9') || (str[i] >= 'A' && str[i] <= 'F')) {
				postfix[j++] = str[i];
			}
			else if (str[i] == '+' || str[i] == '*') {
				if (s.empty()){//stack is empty	
					s.push(str[i]);
				}
				else {
					char c;
					if (!s.empty())
						c = s.top();
					if ((c == '+'&&str[i] == '*') || (c != '*' && str[i] == '+')|| (str[i] == '*')) {//higher precedence 
						s.push(str[i]);
					}
					else{
						postfix[j++] = c;
						if (!s.empty())
						s.pop();
						i--;//Check character again
					}

				}

			}
			else if (str[i] == '(')
				s.push(str[i]);
			else if (str[i] == ')') {
				char c;
				if (!s.empty())
				while ((c = s.top()) != '(') {
					postfix[j++] = c;
					if (!s.empty())
					s.pop();
				}
				if(!s.empty())
				s.pop();	
			}
		}
		while (!s.empty()) {
			char c = s.top();
			s.pop();
			postfix[j++] = c;
		}
		postfix[j++] = '\0';
		for (int i = 0; postfix[i] != '\0'; i++) {
			if ((postfix[i] >= '0'&&postfix[i] <= '9')) {
				result.push(postfix[i]-'0');
			}
			else if (postfix[i] >= 'A' && postfix[i] <= 'F') {
				result.push(postfix[i] - 'A'+10);
			}
			else {
				int n1 = 0; int n2 = 0;
				if (!result.empty())
				n1 = result.top();
				if (!result.empty())
				result.pop();
				if (!result.empty())
				n2 = result.top();
				if (!result.empty())
				result.pop();
				if (postfix[i] == '+') {
					sum = n1 + n2;
					result.push(sum);
				}
				else {
					sum = n1 * n2;
					result.push(sum);
				}
			}
		}
		int d = 0;
		if (!result.empty())
		d = result.top();
		cout <<setiosflags(ios_base::uppercase)<< hex << d<<endl;
	}
	return 0;
}