Submission #477797

#	Time	Username	Problem	Language	Result	Execution time	Memory
477797		mychecksedad	Trener (COCI20_trener)	C++17	110 / 110	824 ms	40904 KiB

trener

/* Author : Mychecksdead */
#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
const int N = 1e6+100, M = 1e5+10, F = 2147483646, K = 20;


ll fp(ll a, ll b){
    ll res = 1;
    while(b){
        if(b & 1) (res *= a) %= MOD;
        (a*=a)%=MOD;
        b>>=1;
    }
    return res;
}
int n, k;
ll dp[55][1600], h[55][1600][55];
string s[55][1600];
void solve(){
    cin >> n >> k;
    for(int i = 1; i <= n; ++i) for(int j = 1; j <= k; ++j) cin >> s[i][j];
    for(int i = 1; i <= n; ++i){
        for(int j = 1; j <= k; ++j){
            h[i][j][0] = 0;
            ll e = 1;
            for(int c = 1; c <= i; ++c, (e*=31)%=MOD){
                h[i][j][c] = (h[i][j][c - 1] + e * (s[i][j][c - 1] - 'a')) % MOD;
            }
        }
    }
    for(int i = 0; i <= n; i++) for(int j = 0; j <= k; ++j) dp[i][j] = 0;
    for(int j = 1; j <= k; ++j) dp[1][j] = 1;
    ll f = fp(31 * 1LL, MOD-2);
    for(int i = 2; i <= n; ++i){
        for(int j = 1; j <= k; ++j){
            for(int back = 1; back <= k; ++back){
                ll l = h[i][j][i - 1];
                ll r = ((((h[i][j][i] - h[i][j][1]) * f)%MOD)+MOD)%MOD;
                if(l == h[i - 1][back][i - 1] || r == h[i - 1][back][i - 1]){
                    (dp[i][j] += dp[i - 1][back]) %= MOD;
                } 
            }
        }
    }
    ll sum = 0;
    for(int i = 1; i <= k; ++i) (sum += dp[n][i]) %= MOD;
    cout << sum;
}



int main(){
    cin.tie(0); ios::sync_with_stdio(0);
    int T = 1, aa;
    // cin >> T;aa=T;
    while(T--){
        // cout << "Case #" << aa-T << ": ";
        solve();
    }
    return 0;
 
}

Compilation message (stderr)

trener.cpp: In function 'int main()':
trener.cpp:62:16: warning: unused variable 'aa' [-Wunused-variable]
   62 |     int T = 1, aa;
      |                ^~

• Subtask 1: 22 / 22
• Subtask 2: 33 / 33
• Subtask 3: 55 / 55