Submission #504881

#	Time	Username	Problem	Language	Result	Execution time	Memory
504881		Carmel_Ab1	Linear Garden (IOI08_linear_garden)	C++17	100 / 100	370 ms	14176 KiB

linear_garden

/*
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
 */
#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>

//using namespace __gnu_pbds;
using namespace std;

typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int>vi;
typedef vector<vector<int>>vvi;
typedef vector<ll>vl;
typedef vector<vl> vvl;
typedef pair<int,int>pi;
typedef pair<ll,ll> pl;
typedef vector<pl> vpl;
typedef vector<ld> vld;
typedef pair<ld,ld> pld;
typedef vector<pi> vpi;

//typedef tree<ll, null_type, less_equal<ll>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
template<typename T> ostream& operator<<(ostream& os, vector<T>& a){os<<"[";for(int i=0; i<ll(a.size()); i++){os << a[i] << ((i!=ll(a.size()-1)?" ":""));}os << "]\n"; return os;}

#define all(x) x.begin(),x.end()
#define YES out("YES")
#define NO out("NO")
#define out(x){cout << x << "\n"; return;}
#define outfl(x){cout << x << endl;return;}
#define GLHF ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define print(x){for(auto ait:x) cout << ait << endl; cout << "\n";}
#define pb push_back
#define umap unordered_map

template<typename T1, typename T2> istream& operator>>(istream& is, pair<T1, T2>& p){is >> p.first >> p.second;return is;}
template<typename T1, typename T2> ostream& operator<<(ostream& os, pair<T1, T2>& p){os <<"" << p.first << " " << p.second << ""; return os;}
void usaco(string taskname){
    string fin = taskname + ".in";
    string fout = taskname + ".out";
    const char* FIN = fin.c_str();
    const char* FOUT = fout.c_str();
    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);
}
template<typename T>
void read(vector<T>& v){
    int n=v.size();
    for(int i=0; i<n; i++)
        cin >> v[i];
}
template<typename T>
vector<T>UNQ(vector<T>a){
    vector<T>ans;
    for(T t:a)
        if(ans.empty() || t!=ans.back())
            ans.push_back(t);
    return ans;
}



void solve();
int main(){
    GLHF;
    int t=1;
    //cin >> t;
    while(t--)
        solve();
}


void solve() {
    ll n,mod;
    cin >> n >> mod;
    string s;
    cin >> s;

    ll ans=0;//how many are lexic. smaller than s

    // L < P !!!


    vi pref_bal(n),pref_mn(n),pref_mx(n);

    pref_bal[0]=(s[0]=='L'?-1:1);
    pref_mx[0]=max(pref_mx[0],pref_bal[0]);
    pref_mn[0]=min(pref_mn[0],pref_bal[0]);

    for(int i=1; i<n; i++){
        pref_bal[i]=pref_bal[i-1]+(s[i]=='L'?-1:1);
        pref_mx[i]=max(pref_mx[i-1],pref_bal[i]);
        pref_mn[i]=min(pref_mn[i-1],pref_bal[i]);
    }

    int dp[5][5][5],prv[5][5][5];
    for(int i=0; i<5; i++)
        for(int j=0; j<5; j++)
            for(int k=0; k<5; k++)
                dp[i][j][k]=prv[i][j][k]=0;




    for(int bal=-2; bal<=2; bal++)
        for(int mx=-2; mx<=2; mx++)
            for(int mn=-2; mn<=mx; mn++)
                if(mx-mn<=2)
                    prv[bal+2][mn+2][mx+2]=1;
    for(int i=n-1; 0<=i; i--) {

        for(int bal=-2; bal<=2; bal++)
            for(int mx=-2; mx<=2; mx++)
                for(int mn=-2; mn<=mx; mn++) {
                    if(mx-mn>2)continue;
                    int v1=(min(mn,bal-1)+2>=0)?prv[bal-1+2][min(mn,bal-1)+2][mx+2]:0;
                    int v2=(max(mx,bal+1)+2<5)?prv[bal+1+2][mn+2][max(mx,bal+1)+2]:0;
                    dp[bal+2][mn+2][mx+2]=(v1+v2)%mod;
                }

        if(s[i]=='L') {
            for(int bal=-2; bal<=2; bal++)
                for(int mx=-2; mx<=2; mx++)
                    for(int mn=-2; mn<=2; mn++)
                        prv[bal+2][mn+2][mx+2]=dp[bal+2][mn+2][mx+2];
            continue;
        }

        int cbal=(i?pref_bal[i-1]:0),cmn=(i?pref_mn[i-1]:0),cmx=(i?pref_mx[i-1]:0);
        cbal--;
        cmn=min(cmn,cbal);
        cmx=max(cmx,cbal);

        ans = (ans + prv[2][cmn-cbal+2][cmx-cbal+2])%mod;

        for(int bal=-2; bal<=2; bal++)
            for(int mx=-2; mx<=2; mx++)
                for(int mn=-2; mn<=2; mn++)
                    prv[bal+2][mn+2][mx+2]=dp[bal+2][mn+2][mx+2];
    }

    ans=(ans+1)%mod;
    out(ans)
}
/*
5
1000000
PLPPL


 12
 100000000
 LPLLPLPPLPLL
 */

Compilation message (stderr)

linear_garden.cpp: In function 'void usaco(std::string)':
linear_garden.cpp:47:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |     freopen(FIN, "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~
linear_garden.cpp:48:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   48 |     freopen(FOUT, "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~

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