Submission #480596

#	Time	Username	Problem	Language	Result	Execution time	Memory
480596		tht2005	Linear Garden (IOI08_linear_garden)	C++17	100 / 100	51 ms	1384 KiB

linear_garden

/**
 *	Magician: tht2005
 *	Spawned: 2021.10.17 14:12:11	
**/

// dp(i, j, k, l) : pos i, j steps to min, k steps to max, l = different from prefix
 
#include <bits/stdc++.h>
using namespace std;
 
int n, md, res, dp[3][3][2], aux[3][3][2];
string s;
 
void add(int& a, int b)
{
	if((a += b) >= md) a -= md;
}
 
int main()
{
	ios::sync_with_stdio(false); cin.tie(NULL);
	cin >> n >> md >> s;
	dp[0][0][0] = 1;
	for(int i = 0; i < n; ++i) {
		for(int j = 0; j < 3; ++j) {
			for(int k = 0; k < 3; ++k) {
				for(int l = 0; l < 2; ++l) {
					aux[j][k][l] = dp[j][k][l];
					dp[j][k][l] = 0;
				}
			}
		}
		for(int j = 0; j < 3; ++j) {
			for(int k = 0; k < 3; ++k) {
				for(int l = 0; l < 2; ++l) {
					int ft = aux[j][k][l];
					if(ft > 0) {
						if(j < 2) add(dp[j + 1][max(0, k - 1)][(int)(l || s[i] == 'P')], ft);
						if((l || s[i] == 'P') && k < 2) add(dp[max(0, j - 1)][k + 1][l], ft);
					}
				}
			}
		}
	}
	res = 0;
	for(int i = 0; i < 3; ++i) {
		for(int j = 0; j < 3; ++j) {
			for(int k = 0; k < 2; ++k) {
				add(res, dp[i][j][k]);
			}
		}
	}
	cout << res;
	return 0;
}

• Subtask 1: 2 / 2
• Subtask 2: 2 / 2
• Subtask 3: 4 / 4
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