BOJ 24731 - XOR-ABC [C++]

문제

링크

풀이

#include <iostream>
#define MOD 1000003
using namespace std;
 
inline long long sub(long long a, long long b) {
  return (a - b + MOD) % MOD;
}
 
inline long long mul(long long a, long long b) {
  return a * b % MOD;
}
 
long long power(long long base, long long exp) {
  long long ret = 1;
  while (exp) {
    if (exp & 1) ret = mul(ret, base);
    base = mul(base, base);
    exp >>= 1;
  }
  return ret;
}
 
void solve(void) {
  long long k; cin >> k;
 
  cout << mul(mul(sub(power(2, k), 1), sub(power(2, k), 2)), power(6, MOD-2));
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}