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답안 #19968

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
19968 2016-02-25T07:56:39 Z Namnamseo 팔찌 (kriii4_V) C++14
6 / 100
 1000 ms 24644 KB 
#include<cstdio>
#include<bitset>
typedef long long ll;
ll M=int(1e9)+7;
ll pow(ll x,ll y){
    if(y==0)return 1;
    if(y==1)return x;
    ll o=pow(x,y/2);
    if(y%2==0)return o*o%M;
    else return o*o%M*x%M;
}
ll ans [1000010];
ll phi [1000010];
ll kpow[1000010];
std::bitset<1000010> sieve;
int n,k;
int main(){
    scanf("%d%d",&n,&k);
    int i,j;
    kpow[0]=1; kpow[1]=k; phi[1]=1;
    for(i=2; i<=n; ++i){
        kpow[i]=kpow[i-1]*k%M;
        if(sieve[i]) continue;
        // i is prime.
        for(j=i; j<=n; j+=i){
            sieve[j]=true;
            if(phi[j]==0) phi[j]=j;
            phi[j] /= i;
            phi[j] *= i-1;
        }
    }
    for(i=1; i<=n; ++i){
        for(j=i; j<=n; j+=i){
            ans[j] += phi[i] * kpow[j/i];
            ans[j] %= M;
        }
    }
    ll tmp, half=pow(2, M-2), sumans = 1;
    for(i=1; i<=n; ++i){
        tmp = ans[i] * half % M * pow(i,M-2) % M;
        sumans += tmp;
        sumans %= M;
        if(i&1){
            sumans += pow(k,(i+1)/2)*half%M;
            sumans %= M;
        } else {
            sumans += (k+1)*half%M*half%M*pow(k,i/2)%M;
            sumans %= M;
        }
    }
    printf("%lld\n",sumans);
    return 0;
}

Subtask #1
6.0 / 6.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 24644 KB Output is correct
2 Correct 0 ms 24644 KB Output is correct
3 Correct 0 ms 24644 KB Output is correct
4 Correct 0 ms 24644 KB Output is correct
5 Correct 0 ms 24644 KB Output is correct
6 Correct 0 ms 24644 KB Output is correct
7 Correct 0 ms 24644 KB Output is correct
8 Correct 0 ms 24644 KB Output is correct
9 Correct 0 ms 24644 KB Output is correct
10 Correct 0 ms 24644 KB Output is correct
11 Correct 0 ms 24644 KB Output is correct
12 Correct 0 ms 24644 KB Output is correct
13 Correct 0 ms 24644 KB Output is correct
14 Correct 0 ms 24644 KB Output is correct
15 Correct 0 ms 24644 KB Output is correct
16 Correct 0 ms 24644 KB Output is correct
17 Correct 0 ms 24644 KB Output is correct
18 Correct 0 ms 24644 KB Output is correct
19 Correct 0 ms 24644 KB Output is correct
20 Correct 0 ms 24644 KB Output is correct

Subtask #2
0.0 / 94.0

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 24644 KB Output is correct
2 Correct 0 ms 24644 KB Output is correct
3 Correct 2 ms 24644 KB Output is correct
4 Correct 99 ms 24644 KB Output is correct
5 Execution timed out 1000 ms 24644 KB Program timed out
6 Halted 0 ms 0 KB -