Submission #1036572

#	Time	Username	Problem	Language	Result	Execution time	Memory
1036572		VMaksimoski008	Linear Garden (IOI08_linear_garden)	C++17	50 / 100	26 ms	13600 KiB

linear_garden

#include <bits/stdc++.h>

#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
//#define int long long

using namespace std;

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

const int LOG = 20;
const int maxn = 1e5 + 5;

ll n, mod, ans = 0;
vector<ll> vec;
string s;

//neka L = -1 i P = 1
//togas abs(pref[i] - pref[j-1]) <= 2 za site i, j
//ako celo vreme cuvame min pref suma i max pref suma, treba abs(max - min) <= 2
//drugite 2 dimenzii se under i started

ll dp[1005][5][5][5][2];

ll f(int pos, int mn, int mx, int curr, int under) {
    if(mx - mn > 2) return 0;
    if(mx > 4 || mn < 0) return 0;
    if(pos == n + 1) return under;
    // cerr << pos << " " << mn << " " << mx << " " << curr << " " << under << '\n';
    if(dp[pos][mn][mx][curr][under] != -1) return dp[pos][mn][mx][curr][under];

    ll ans = 0;

    //try putting -1
    for(int i=-1; i<=1; i++) {
        if(i == 0) continue;
        if(!under && i > vec[pos]) continue;
        int nmn = min(mn, curr + i);
        int nmx = max(mx, curr + i);
        int nu = under | (i < vec[pos]);
        ans = (ans + f(pos+1, nmn, nmx, curr + i, nu)) % mod;
    }

    return dp[pos][mn][mx][curr][under] = ans;
}

signed main() {
    memset(dp, -1, sizeof(dp));
    cin >> n >> mod >> s;
    vec.push_back(0);

    if(n <= 10) {
        vector<string> vec;
        for(int s=0; s<(1<<n); s++) {
            string t = "";
            for(int i=0; i<n; i++) {
                if(s & (1 << i)) t += '1';
                else t += '0';
            }
    
            bool ok = 1;
            for(int i=0; i<n&&ok; i++) {
                int cnt = 0;
                for(int j=i; j<n&&ok; j++) {
                    if(t[j] == '1') cnt++;
                    else cnt--;
    
                    if(cnt > 2 || cnt < -2)  ok = 0;
                }
            }
    
            if(ok) vec.push_back(t);
        }
    
        sort(vec.begin(), vec.end());
    
        for(int i=0; i<vec.size(); i++) {
            if(vec[i] == s) {
                cout << (i + 1) % mod << '\n';
                return 0;
            }
        }
    }

    for(int i=0; i<n; i++) {
        if(s[i] == 'L') vec.push_back(-1);
        else vec.push_back(1);
    }

    ll ans = f(1, 2, 2, 2, 0);
    cout << (ans + 1) % mod << '\n';
    return 0;
}

Compilation message (stderr)

linear_garden.cpp: In function 'int main()':
linear_garden.cpp:79:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |         for(int i=0; i<vec.size(); i++) {
      |                      ~^~~~~~~~~~~

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