BOJ 15824 - 너 봄에는 캡사이신이 맛있단다 [C++]

문제

링크

풀이

#include <iostream>
#include <vector>
#include <algorithm>
#define MOD 1000000007
using namespace std;
 
long long power(long long base, long long exp) {
  long long ret = 1;
  while (exp) {
    if (exp & 1) ret = (ret * base) % MOD;
    base = (base * base) % MOD;
    exp >>= 1;
  }
  return ret;
}
 
void solve(void) {
  int n; cin >> n;
  vector<long long> a(n);
  for (int i=0; i<n; i++) cin >> a[i];
  sort(a.begin(), a.end());
 
  long long ans = 0;
  for (int i=0; i<n; i++) {
    ans = (ans + (a[i] * power(2, i)) % MOD - (a[i] * power(2, n-i-1)) % MOD + MOD) % MOD;
  }
  cout << ans;
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}