AorB HackerRank C++ code study #2

AorB_studyCplusplus_2.cpp

#include <bits/stdc++.h>

#define all(x) (x).begin(), (x).end()
#define li long long
#define itn int

using namespace std;

inline int nxt(){
	int n;
	scanf("%d", &n);
	return n;
}

int gcd(int x, int y){
	while (y){
		x %= y;
		swap(x, y);
	}
	return x;
}

const int mod = 1000000007;

vector<bool> getlol(){
	string s;
	cin >> s;
	vector<bool> res;
	for (auto c : s){
		int x = (c >= '0' && c <= '9') ? c - '0' : c - 'A' + 10;
		for (int i = 0; i < 4; i++){
			res.push_back((x & (1 << (3 - i))) ? 1 : 0);
		}
	}
	return res;
}

string xui(const vector<bool>& a){
	string res = "";
	for (int i = 0; i < a.size(); i += 4){
		int x = 0;
		for (int j = 0; j < 4; j++){
			x *= 2;
			if (a[i + j])
				x++;
		}
		res += (x < 10 ? '0' + x : 'A' + (x - 10));
	}
	int i = 0;
	while (i < (int)res.length() - 1 && res[i] == '0')
		i++;
	return res.substr(i);
}

int main(){

	cin.sync_with_stdio(0);
	cout.sync_with_stdio(0);
	int T;
	cin >> T;
	while (T--){
		int k;
		cin >> k;
		auto a = getlol();
		auto b = getlol();
		auto c = getlol();

		int n = a.size();
		if (b.size() > n)
			n = b.size();
		if (c.size() > n)
			n = c.size();
		reverse(all(a));
		reverse(all(b));
		reverse(all(c));
		a.resize(n, 0);
		b.resize(n, 0);
		c.resize(n, 0);
		reverse(all(a));
		reverse(all(b));
		reverse(all(c));
		for (int i = 0; i < n; i++){
			if (c[i] == 0){
				if (a[i]){
					a[i] = 0;
					k--;
				}
				if (b[i]){
					b[i] = 0;
					k--;
				}
			} else {
				if (a[i] == 0 && b[i] == 0){
					b[i] = 1;
					k--;
				}
			}
		}
		if (k < 0){
			cout << "-1\n";
		} else {
			for (int i = 0; i < n && k; i++){
				if (c[i]){
					if (a[i] && b[i]){
						a[i] = 0;
						k--;
					} else if (a[i]){
						if (k >= 2){
							a[i] = 0;
							b[i] = 1;
							k -= 2;
						}
					}
				}
			}
			cout << xui(a) << "\n" << xui(b) << "\n";
		}
	}

	return 0;
}