Submission #20092

#	Time	Username	Problem	Language	Result	Execution time	Memory
20092		kk1401	괄호 (kriii4_R)	C++98	0 / 100	17 ms	24520 KiB

R

#include<stdio.h>
#define M 1000000007ll

int n;
long long d[1000001],k,pow[1000001],comb[1000001];

int main()
{
	int i;
	
	scanf("%d%lld",&n,&k);
	
	d[1] = k;
	
	pow[0]=1ll;
	for(i=1; i<=n; i++) pow[i] = (pow[i-1] * k) % M;
	
	comb[1] = 2;
	for(i=2; i<=n; i++) comb[i] = ((comb[i-1] / (long long)i) * (4ll*(long long)i - 2ll)) % M;
	
	for(i=2; i<=n; i++){
		if(i%2 == 0) d[i] = (d[i-1] * (k + 1ll)) % M;
		else d[i] = (d[i-1] * (k + 1ll) - pow[(i-1)/2] * comb[(i-1)/2] / (((long long)i-1ll)/2ll+1ll) + M * M) % M;
	}
	
	printf("%lld\n",d[n]);
	
	return 0;
}

• Subtask 1: 0 / 8
• Subtask 2: 0 / 92