oj.uz

답안 #19915

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
19915 2016-02-25T07:02:54 Z cki86201 팔찌 (kriii4_V) C++14
6 / 100
 1000 ms 17348 KB 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <math.h>
#include <assert.h>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <string>
#include <algorithm>
#include <iostream>
#include <functional>
#include <unordered_map>
#include <unordered_set>

using namespace std;
typedef long long ll;
typedef pair<int, int> Pi;
#define Fi first
#define Se second
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define rep(i,n) for(int i=0;i<n;i++)
#define all(x) x.begin(),x.end()

const ll MOD = 1e9 + 7;

ll pw(ll x, ll y){
	ll res = 1;
	while(y){
		if(y & 1)res = res * x % MOD;
		x = x * x % MOD;
		y >>= 1;
	}
	return res;
}

ll pwk[1000010];
int phi[1000010];
int isp[1000010];

int main(){
	int N, K;
	scanf("%d%d", &N, &K);
	pwk[0] = 1;
	for(int i=1;i<1000010;i++)pwk[i] = K * pwk[i-1] % MOD;
	phi[1] = 1;
	for(int i=2;i<1000010;i++)phi[i] = i, isp[i] = 1;
	for(int i=2;i<1000010;i++){
		if(isp[i]){
			phi[i] = i-1;
			for(int j=i+i;j<1000010;j+=i){
				isp[j] = 0;
				phi[j] /= i;
				phi[j] *= (i-1);
			}
		}
	}
	ll ans = 1;
	ll p2 = pw(2, MOD-2);
	ll p4 = pw(4, MOD-2);
	for(int i=1;i<=N;i++){
		ll sum = 0;
		for(int j=1;j*j<=i;j++){
			if(i % j != 0)continue;
			sum += phi[j] * pwk[i/j];
			sum %= MOD;
			if(j*j != i){
				sum += phi[i/j] * pwk[j];
				sum %= MOD;
			}
		}
		//printf("%d %lld\n", i, sum);
		ans += sum * pw(2*i, MOD-2);
		if(i & 1)ans += p2 * pwk[(i+1)/2];
		else ans += p4 * (K+1) % MOD * pwk[i/2];
		ans %= MOD;
	}
	printf("%lld", ans);
	return 0;
}

Subtask #1
6.0 / 6.0

# 결과 실행 시간 메모리 Grader output
1 Correct 49 ms 17348 KB Output is correct
2 Correct 47 ms 17348 KB Output is correct
3 Correct 47 ms 17348 KB Output is correct
4 Correct 40 ms 17348 KB Output is correct
5 Correct 47 ms 17348 KB Output is correct
6 Correct 50 ms 17348 KB Output is correct
7 Correct 43 ms 17348 KB Output is correct
8 Correct 50 ms 17348 KB Output is correct
9 Correct 46 ms 17348 KB Output is correct
10 Correct 42 ms 17348 KB Output is correct
11 Correct 47 ms 17348 KB Output is correct
12 Correct 47 ms 17348 KB Output is correct
13 Correct 50 ms 17348 KB Output is correct
14 Correct 50 ms 17348 KB Output is correct
15 Correct 50 ms 17348 KB Output is correct
16 Correct 46 ms 17348 KB Output is correct
17 Correct 49 ms 17348 KB Output is correct
18 Correct 46 ms 17348 KB Output is correct
19 Correct 50 ms 17348 KB Output is correct
20 Correct 50 ms 17348 KB Output is correct

Subtask #2
0.0 / 94.0

# 결과 실행 시간 메모리 Grader output
1 Correct 43 ms 17348 KB Output is correct
2 Correct 47 ms 17348 KB Output is correct
3 Correct 48 ms 17348 KB Output is correct
4 Correct 118 ms 17348 KB Output is correct
5 Execution timed out 1000 ms 17344 KB Program timed out
6 Halted 0 ms 0 KB -