Submission #995838

#	Time	Username	Problem	Language	Result	Execution time	Memory
995838		biank	Linear Garden (IOI08_linear_garden)	C++14	100 / 100	899 ms	2552 KiB

linear_garden

#include <bits/stdc++.h>

using namespace std;

int prev_dp[5][5][3][2];
int curr_dp[5][5][3][2];
int n, m;
string g;

int getVal(int curr_diff, int min_diff, int max_diff, bool tight) {
    if (curr_diff < 0 || curr_diff >= 5) return 0;
    if (max_diff - min_diff >= 3) return 0;
    return prev_dp[curr_diff][min_diff][max_diff - min_diff][tight];
}

void compute(int pos, int curr_diff, int min_diff, int max_diff, bool tight) {
    int &res = curr_dp[curr_diff][min_diff][max_diff - min_diff][tight];
    res = getVal(curr_diff + 1, min_diff, max(max_diff, curr_diff + 1), tight && g[pos] == 'L');
    if (!tight || g[pos] == 'P') {
        res += getVal(curr_diff - 1, min(min_diff, curr_diff - 1), max_diff, tight && g[pos] == 'P');
        if (res >= m) res -= m;
    }
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    
    cin >> n >> m >> g;
    for (int curr_diff = 0; curr_diff < 5; curr_diff++) {
        for (int min_diff = 0; min_diff < 5; min_diff++) {
            for (int max_diff = min_diff; max_diff - min_diff < 3; max_diff++) {
                for (bool tight : {false, true}) {
                    prev_dp[curr_diff][min_diff][max_diff - min_diff][tight] = 1;
                }
            }
        }
    }
    for (int pos = n - 1; pos >= 0; pos--) {
        for (int curr_diff = 0; curr_diff < 5; curr_diff++) {
            for (int min_diff = 0; min_diff < 5; min_diff++) {
                for (int max_diff = min_diff; max_diff - min_diff < 3; max_diff++) {
                    for (bool tight : {false, true}) {
                        compute(pos, curr_diff, min_diff, max_diff, tight);
                    }
                }
            }
        }
        for (int curr_diff = 0; curr_diff < 5; curr_diff++) {
            for (int min_diff = 0; min_diff < 5; min_diff++) {
                for (int max_diff = min_diff; max_diff - min_diff < 3; max_diff++) {
                    for (bool tight : {false, true}) {
                        prev_dp[curr_diff][min_diff][max_diff - min_diff][tight] = curr_dp[curr_diff][min_diff][max_diff - min_diff][tight];
                        curr_dp[curr_diff][min_diff][max_diff - min_diff][tight] = 0;
                    }
                }
            }
        }
    }
    cout << prev_dp[2][2][0][1] << '\n';
    
    
    return 0;
}

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