Submission #693200

#	Time	Username	Problem	Language	Result	Execution time	Memory
693200		testttt	Rack (eJOI19_rack)	C++14	0 / 100	1 ms	300 KiB

rack

#include <bits/stdc++.h>

using namespace std;

#define ll long long

const ll mod = 1e9 + 7;

long long exp(long long x, long long y, long long p) {
	long long res = 1; x %= p;
	while (y) {
		if (y & 1) {
			res *= x; res %= p; 
		}
		x *= x; x %= p;
		y >>= 1;
	}
	return res;
}

int main(){
    ll n , k;cin >> n >> k;
    -- k;
    ll ans = 1;
    for(int i = 0;i <= log(k) + 1;i ++){
        if((1 << i) & k){
            (ans += exp(2 , n - i - 1 , mod)) % mod;
        }
    }
    cout << ans << endl;
}

Compilation message (stderr)

rack.cpp: In function 'int main()':
rack.cpp:27:47: warning: value computed is not used [-Wunused-value]
   27 |             (ans += exp(2 , n - i - 1 , mod)) % mod;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~

• Subtask 1: 0 / 20
• Subtask 2: 0 / 20
• Subtask 3: 0 / 60