Submission #19009

#	TimeUTC-0	Username	Problem	Language	Result	Execution time	Memory
19009	2016-02-17 02:57:59	kriii	괄호 (kriii4_R)	C++14	100 / 100	38 ms	8896 KiB

R

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#include <stdio.h>
const long long mod = 1000000007;
long long inv[500002],cat[500001];
int main()
{
  int n,k; scanf ("%d %d",&n,&k);
  inv[1] = 1;
  for (int i=2;i<=n/2+1;i++) inv[i] = (mod - mod / i) * inv[mod % i] % mod;
  cat[0] = 1;
  for (int i=1;i<=n/2;i++) cat[i] = (4 * i - 2) * inv[i+1] % mod * cat[i-1] % mod;
  long long u = 1;
  for (int i=1;i<=n/2;i++){
    u = u * k % mod;
    cat[i] = cat[i] * u % mod;
  }
  long long ans = 1;
  for (int i=0;i<n;i++){
    ans = ans * (k + 1) % mod;
    if (i % 2 == 0) ans = (ans + mod - cat[i/2]) % mod;
  }
  printf ("%lld\n",ans);
  return 0;
 
 
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• Subtask 1: 8 / 8
• Subtask 2: 92 / 92