UVA_446_Kibbles "n" Bits "n" Bits "n" Bits

#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<algorithm>
#include<bitset>
#pragma warning(disable:4996)
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
using std::priority_queue;
using std::bitset;
int HexToDecimal(const string &hex)
{
int ret = 0;
for (size_t i = 0; i < hex.size(); i++)
{
ret *= 16;
switch (hex[i])
{
case '0':ret += 0; break;
case '1':ret += 1; break;
case '2':ret += 2; break;
case '3':ret += 3; break;
case '4':ret += 4; break;
case '5':ret += 5; break;
case '6':ret += 6; break;
case '7':ret += 7; break;
case '8':ret += 8; break;
case '9':ret += 9; break;
case 'A':ret += 10; break;
case 'B':ret += 11; break;
case 'C':ret += 12; break;
case 'D':ret += 13; break;
case 'E':ret += 14; break;
case 'F':ret += 15; break;
default:break;
}
}
return ret;
}
int main()
{
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
int T;
while (cin >> T)
{
cin.get();
while (T--)
{
string hex1, Operator, hex2;
cin >> hex1 >> Operator >> hex2;
auto decimal1 = HexToDecimal(hex1);
auto decimal2 = HexToDecimal(hex2);
cout << bitset<13>(decimal1) << ' '<< Operator<<' ' << bitset<13>(decimal2) << " = ";
if (Operator == "+")
{
cout << decimal1 + decimal2 << endl;
}
else
{
cout << decimal1 - decimal2 << endl;
}
}
}
return 0;
}