제출 #228377

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
228377		FieryPhoenix	Linear Garden (IOI08_linear_garden)	C++11	100 / 100	222 ms	10404 KiB

linear_garden

#include <bits/stdc++.h>
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
typedef long long ll;
typedef long double ld;
#define INF 2001001001
#define MOD 1000000007

int N,M;
string S;
int dp[2][3][3][2];//index, max(L-P), max(P-L), 0 for L

int L_P[10000001],P_L[10000001];

int main()
{
  //ios_base::sync_with_stdio(0);cin.tie(0);
  //freopen (".in","r",stdin);
  //freopen (".out","w",stdout);
  cin>>N>>M;
  cin>>S;
  for (int i=0;i<N;i++){
    if (S[i]=='L'){
      L_P[i+1]=L_P[i]+1;
      P_L[i+1]=max(0,P_L[i]-1);
    }
    else{
      P_L[i+1]=P_L[i]+1;
      L_P[i+1]=max(0,L_P[i]-1);
    }
  }
  dp[0][0][0][0]=1;
  int ind=1,nind=0;
  int ans=0;
  for (int i=N-1;i>=0;i--){
    //adding L
    for (int j=0;j<2;j++)
      for (int k=0;k<=2;k++)
	for (int l=0;l<2;l++){
	  dp[ind][j+1][max(0,k-1)][0]+=dp[nind][j][k][l];
	  dp[ind][j+1][max(0,k-1)][0]%=M;
	}
    //adding P
    for (int j=0;j<=2;j++)
      for (int k=0;k<2;k++)
	for (int l=0;l<2;l++){
	  dp[ind][max(0,j-1)][k+1][1]+=dp[nind][j][k][l];
	  dp[ind][max(0,j-1)][k+1][1]%=M;
	}
    if (S[i]=='P'){
      for (int j=0;j<=2;j++)
	for (int k=0;k<=2;k++)
	  if (j+L_P[i]<=2 && k+P_L[i]<=2){
	    //cout<<"add "<<dp[ind][j][k][0]<<endl;
	    ans+=dp[ind][j][k][0];
	    ans%=M;
	  }
    }
    for (int j=0;j<=2;j++)
      for (int k=0;k<=2;k++)
	for (int l=0;l<2;l++){
	  dp[nind][j][k][l]=0;
	}
    swap(ind,nind);
  }
  cout<<(ans+1)%M<<endl;
  return 0;
}

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