Submission #410400

#	Time	Username	Problem	Language	Result	Execution time	Memory
410400		Jasiekstrz	Linear Garden (IOI08_linear_garden)	C++17	100 / 100	77 ms	37596 KiB

linear_garden

#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const int N=1e6;
int mod;
int dp[N+10][3][3];
int ask(int n,int l,int r)
{
	if(r+l>2)
		return 0;
	if(r+l==2)
		return dp[n][l][r];
	// l=0, r=1
	return (dp[n][0][2]+dp[n][1][1]-dp[n][0][1])%mod;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int n;
	cin>>n>>mod;
	for(int j=0;j<=2;j++)
	{
		for(int k=0;k<=2;k++)
			dp[0][j][k]=1;
	}
	for(int i=0;i<n;i++)
	{
		for(int j=0;j<=2;j++)
		{
			for(int k=0;k<=2;k++)
			{
				if(j-1>=0 && k+1<=2)
				{
					dp[i+1][j-1][k+1]+=dp[i][j][k];
					dp[i+1][j-1][k+1]%=mod;
				}
				if(k-1>=0 && j+1<=2)
				{
					dp[i+1][j+1][k-1]+=dp[i][j][k];
					dp[i+1][j+1][k-1]%=mod;
				}
			}
		}
	}
	string s;
	cin>>s;
	int ans=1;
	int sum=0;
	int l=0,r=0;
	for(int i=1;i<=n;i++)
	{
		int x=(s[i-1]=='L' ? -1:1);
		if(x==1)
		{
			int tmps=sum-1,tmpl=max(l,-tmps),tmpr=max(r,tmps);
			ans+=ask(n-i,tmpl+tmps,tmpr-tmps);
			ans%=mod;
		}		
		sum+=x;
		l=max(l,-sum);
		r=max(r,sum);
	}
	cout<<(ans%mod+mod)%mod<<"\n";
	return 0;
}

• Subtask 1: 2 / 2
• Subtask 2: 2 / 2
• Subtask 3: 4 / 4
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 4 / 4
• Subtask 7: 4 / 4
• Subtask 8: 4 / 4
• Subtask 9: 4 / 4
• Subtask 10: 4 / 4
• Subtask 11: 4 / 4
• Subtask 12: 5 / 5
• Subtask 13: 5 / 5
• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5
• Subtask 21: 5 / 5
• Subtask 22: 5 / 5
• Subtask 23: 5 / 5