Submission #107740

#	Time	Username	Problem	Language	Result	Execution time	Memory
107740		luciocf	Linear Garden (IOI08_linear_garden)	C++14	100 / 100	859 ms	2468 KiB

linear_garden

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e6+10;
const int delta = 5;

int n, mod;

// pos, dif, Max L-R, Max R-L, Prefixo/menor
// -1 -> 4
// -2 -> 3
int dp[2][5][3][3][2];

char s[maxn];

bool bad(int dif, int mx)
{
	if (dif > 2 || (dif == 2 && mx > 0) || (dif == 1 && mx > 1)) return 1;
	return 0;
}

void add(int &a, int &b)
{
	a = (a+b)%mod;
}

void init(int cur)
{
	for (int j = 0; j < 5; j++)
		for (int l = 0; l < 3; l++)
			for (int p = 0; p < 3; p++)
				for (int m = 0; m < 2; m++)
					dp[cur][j][l][p][m] = 0;
}

int main(void)
{
	scanf("%d %d", &n, &mod);

	for (int i = 1; i <= n; i++)
		scanf(" %c", &s[i]);

	if (s[1] == 'L') dp[1][1][1][0][1] = 1;
	else
	{
		dp[1][-1+delta][0][1][1] = 1;
		dp[1][1][1][0][0] = 1;
	}

	for (int i = 1; i < n; i++)
	{
		int cur = (i+1)%2, ant = i%2;

		init(cur);

		for (int j = 0; j < 5; j++)
		{
			for (int l = 0; l < 3; l++)
			{
				for (int p = 0; p < 3; p++)
				{
					for (int m = 0; m < 2; m++)
					{
						int dif = (j <= 2 ? j : abs(j-delta));

						if (j <= 2 && bad(dif, p)) continue;
						if (j > 2 && bad(dif, l)) continue;

						// colocar L
						if ((j > 2 && !bad(dif-1, l)) || !bad(dif+1, p))
						{
							int e;
							if (m == 0 || s[i+1] == 'P') e = 0;
							else e = 1;

							if (j > 2)
							{
								int newdif = (j == 3 ? 4 : 0);
								add(dp[cur][newdif][l][p][e], dp[ant][j][l][p][m]);
							}
							else
							{
								int newdif = dif+1, newmax = max(l, newdif);
								add(dp[cur][newdif][newmax][p][e], dp[ant][j][l][p][m]);
							}
						}

						// colocar P
						if ((j > 0 && j <= 2 && !bad(dif-1, p)) || !bad(dif+1, l))
						{
							if (m && s[i+1] == 'L') continue;

							int e = m;

							if (j == 0)
							{
								int newdif = 4, newmax = max(p, 1);
								add(dp[cur][newdif][l][newmax][e], dp[ant][j][l][p][m]);
							}
							else if (j <= 2)
							{
								int newdif = dif-1;
								add(dp[cur][newdif][l][p][e], dp[ant][j][l][p][m]);
							}
							else
							{
								int newdif = 3, newmax = max(p, dif+1);
								add(dp[cur][newdif][l][newmax][e], dp[ant][j][l][p][m]);
							}
						}
					}
				}
			}
		}
	}

	int ans = 0;
	for (int j = 0; j < 5; j++)
		for (int l = 0; l < 3; l++)
			for (int p = 0; p < 3; p++)
				add(ans, dp[n%2][j][l][p][0]);

	ans = (ans+1)%mod;

	printf("%d\n", ans);
}

Compilation message (stderr)

linear_garden.cpp: In function 'int main()':
linear_garden.cpp:39:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &mod);
  ~~~~~^~~~~~~~~~~~~~~~~~~
linear_garden.cpp:42:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf(" %c", &s[i]);
   ~~~~~^~~~~~~~~~~~~~

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