#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 F[2000010], iF[2000020];
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 nCr(int x, int y){
return F[x] * iF[y] % MOD * iF[x-y] % MOD;
}
int main(){
F[0] = 1;
for(int i=1;i<2000010;i++)F[i] = i * F[i-1] % MOD;
iF[0] = 1;
for(int i=1;i<2000010;i++)iF[i] = pw(F[i], MOD-2);
int N, K;
scanf("%d%d", &N, &K);
ll ans = 0;
for(int i=(N&1);i<=N;i+=2){
int a = (N-i)/2;
int b = (N+i)/2;
//printf("%d %d\n", a, b);
ll g;
if(a > 0)g = (nCr(a+b, b) - nCr(a+b, b+1) + MOD) % MOD;
else g = 1;
ans = (ans + pw(K, b) * g) % MOD;
}
printf("%lld", ans);
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
540 ms |
32972 KB |
Output is correct |
| 2 |
Correct |
510 ms |
32972 KB |
Output is correct |
| 3 |
Correct |
577 ms |
32972 KB |
Output is correct |
| 4 |
Correct |
593 ms |
32972 KB |
Output is correct |
| 5 |
Correct |
593 ms |
32972 KB |
Output is correct |
| 6 |
Correct |
550 ms |
32972 KB |
Output is correct |
| 7 |
Correct |
560 ms |
32972 KB |
Output is correct |
| 8 |
Correct |
543 ms |
32972 KB |
Output is correct |
| 9 |
Correct |
526 ms |
32972 KB |
Output is correct |
| 10 |
Correct |
504 ms |
32972 KB |
Output is correct |
| 11 |
Correct |
511 ms |
32972 KB |
Output is correct |
| 12 |
Correct |
583 ms |
32972 KB |
Output is correct |
| 13 |
Correct |
571 ms |
32972 KB |
Output is correct |
| 14 |
Correct |
540 ms |
32972 KB |
Output is correct |
| 15 |
Correct |
541 ms |
32972 KB |
Output is correct |
| 16 |
Correct |
534 ms |
32972 KB |
Output is correct |
| 17 |
Correct |
599 ms |
32972 KB |
Output is correct |
| 18 |
Correct |
594 ms |
32972 KB |
Output is correct |
| 19 |
Correct |
603 ms |
32972 KB |
Output is correct |
| 20 |
Correct |
603 ms |
32972 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
528 ms |
32972 KB |
Output is correct |
| 2 |
Correct |
508 ms |
32972 KB |
Output is correct |
| 3 |
Correct |
515 ms |
32972 KB |
Output is correct |
| 4 |
Correct |
597 ms |
32972 KB |
Output is correct |
| 5 |
Correct |
568 ms |
32972 KB |
Output is correct |
| 6 |
Correct |
581 ms |
32972 KB |
Output is correct |
| 7 |
Correct |
558 ms |
32972 KB |
Output is correct |
| 8 |
Correct |
536 ms |
32972 KB |
Output is correct |
| 9 |
Correct |
556 ms |
32972 KB |
Output is correct |
| 10 |
Correct |
522 ms |
32972 KB |
Output is correct |
| 11 |
Correct |
588 ms |
32972 KB |
Output is correct |
| 12 |
Correct |
586 ms |
32972 KB |
Output is correct |
| 13 |
Correct |
588 ms |
32972 KB |
Output is correct |
| 14 |
Correct |
546 ms |
32972 KB |
Output is correct |
| 15 |
Correct |
549 ms |
32972 KB |
Output is correct |
| 16 |
Correct |
554 ms |
32972 KB |
Output is correct |
| 17 |
Correct |
519 ms |
32972 KB |
Output is correct |
| 18 |
Correct |
608 ms |
32972 KB |
Output is correct |
| 19 |
Correct |
607 ms |
32972 KB |
Output is correct |
| 20 |
Correct |
601 ms |
32972 KB |
Output is correct |
