CSES - Putka Open 2025 – 4/5

Submission details
Task:	Merkkijonot
Sender:	jlaire
Submission time:	2025-11-08 01:56:56 +0200
Language:	C++ (C++17)
Status:	READY
Result:	0

Feedback
group	verdict	score
#1	WRONG ANSWER	0
#2	WRONG ANSWER	0
#3	WRONG ANSWER	0
#4	WRONG ANSWER	0
#5	WRONG ANSWER	0

Test results
test	verdict	time	group
#1	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#2	ACCEPTED	0.01 s	2, 3, 4, 5	details
#3	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#4	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#5	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#6	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#7	WRONG ANSWER	0.00 s	1, 2, 3, 4, 5	details
#8	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#9	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#10	ACCEPTED	0.00 s	1, 2, 3, 4, 5	details
#11	ACCEPTED	0.01 s	2, 3, 4, 5	details
#12	ACCEPTED	0.02 s	2, 3, 4, 5	details
#13	ACCEPTED	0.02 s	2, 3, 4, 5	details
#14	ACCEPTED	0.02 s	2, 3, 4, 5	details
#15	WRONG ANSWER	0.00 s	2, 3, 4, 5	details
#16	ACCEPTED	0.02 s	2, 3, 4, 5	details
#17	WRONG ANSWER	0.01 s	2, 3, 4, 5	details
#18	ACCEPTED	0.02 s	2, 3, 4, 5	details
#19	WRONG ANSWER	0.01 s	3, 4, 5	details
#20	WRONG ANSWER	0.03 s	3, 4, 5	details
#21	WRONG ANSWER	0.03 s	3, 4, 5	details
#22	WRONG ANSWER	0.03 s	3, 4, 5	details
#23	WRONG ANSWER	0.00 s	3, 4, 5	details
#24	WRONG ANSWER	0.04 s	3, 4, 5	details
#25	WRONG ANSWER	0.01 s	3, 4, 5	details
#26	WRONG ANSWER	0.03 s	3, 4, 5	details
#27	WRONG ANSWER	0.01 s	4, 5	details
#28	WRONG ANSWER	0.04 s	4, 5	details
#29	WRONG ANSWER	0.05 s	4, 5	details
#30	WRONG ANSWER	0.04 s	4, 5	details
#31	WRONG ANSWER	0.00 s	4, 5	details
#32	WRONG ANSWER	0.05 s	4, 5	details
#33	WRONG ANSWER	0.01 s	4, 5	details
#34	WRONG ANSWER	0.04 s	4, 5	details
#35	WRONG ANSWER	0.01 s	5	details
#36	WRONG ANSWER	0.06 s	5	details
#37	WRONG ANSWER	0.06 s	5	details
#38	WRONG ANSWER	0.05 s	5	details
#39	WRONG ANSWER	0.00 s	5	details
#40	WRONG ANSWER	0.06 s	5	details
#41	WRONG ANSWER	0.01 s	5	details
#42	WRONG ANSWER	0.05 s	5	details

Code

#include <algorithm>
#include <cassert>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>
using namespace std;
using ll = long long;
using vll = vector<ll>;

const ll MOD = 1e9 + 7;

namespace {
// library
ll modpow(ll b, ll e) {
    ll ans = 1;
    for (; e; b = b * b % MOD, e /= 2)
        if (e & 1) ans = ans * b % MOD;
    return ans;
}

vll berlekampMassey(vll s) {
    int n = s.size(), L = 0, m = 0;
    if (!n) return {};
    vll C(n), B(n), T;
    C[0] = B[0] = 1;
    ll b = 1;
    for (int i=0; i<n; i++) {
        ++m;
        ll d = s[i] % MOD;
        for (int j=1; j<L+1; j++) d = (d + C[j] * s[i - j]) % MOD;
        if (!d) continue;
        T = C;
        ll coef = d * modpow(b, MOD - 2) % MOD;
        for (int j=m; j<n; j++) C[j] = (C[j] - coef * B[j - m]) % MOD;
        if (2 * L > i) continue;
        L = i + 1 - L;
        B = T;
        b = d;
        m = 0;
    }
    C.resize(L + 1);
    C.erase(C.begin());
    for (ll &x : C) x = (MOD - x) % MOD;
    return C;
}

template <typename T>
vector<vector<T>> prod(vector<vector<T>> &a, vector<vector<T>> &b, const ll mod) {
    assert(a.back().size() == b.size());
    int n = a.size();
    int m = a.back().size();
    vector<vector<T>> c(n, vector<T>(m));
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            for (int k = 0; k < m; k++)
                c[i][j] = (c[i][j] + ((a[i][k] * b[k][j]) % mod)) % mod;
    return c;
}

template <typename T>
vector<vector<T>> fpow(vector<vector<T>> &xs, ll p, ll mod) {
    vector<vector<T>> ans(xs.size(), vector<T>(xs.size()));
    for (int i = 0; i < (int)xs.size(); i++) ans[i][i] = 1;
    for (auto b = xs; p; p >>= 1, b = prod(b, b, mod))
        if (p & 1) ans = prod(ans, b, mod);
    return ans;
}

ll linear_req(vector<vector<ll>> rec, vector<ll> first_k, ll n, const ll mod) {
    int k = first_k.size();
    if (n <= k) return first_k[n - 1];
    ll n2 = n - k;
    rec = fpow(rec, n2, mod);
    ll ret = 0;
    for (int i = 0; i < k; i++)
        ret = (ret + (rec.back()[i] * first_k[i]) % mod) % mod;
    return ret;
}
}

ll go(vector<map<ll,ll>>& dp, ll mask, ll todo, const string& X) {
    if (todo == 0) return mask&1;
    if (dp[todo].count(mask)) return dp[todo][mask];
    ll ans = 0;
    int m = X.size();
    for (char c='a'; c<='z'; c++) {
        ll m2 = 0;
        for (int i=1; i<m; i++) if (X[i]==c) {
            if (mask & (1|(1ll<<(m-i)))) {
                m2 |= 1ll << (m-i-1);
            }
        }
        if (X[0]==c) {
            m2 |= 1ll<<(m-1);
        }
        if (!m2) continue;
        ans += go(dp, m2, todo-1, X);
        ans %= MOD;
    }
    return dp[todo][mask] = ans;
}

ll solve(ll n, string X) {
    vll seed;
    ll SS=10+2*X.size();
    vector<map<ll,ll>> dp(SS+X.size());
    for (int i=0; i<SS; i++) {
        seed.push_back(go(dp, 1ll<<X.size(), X.size()+i, X));
    }
    vll ff = berlekampMassey(seed);
    int K = ff.size();
    vector<vll> mat(K, vll(K));
    for (int i=0; i<K-1; i++) mat[i][i+1] = 1;
    mat[K-1] = ff;
    reverse(mat[K-1].begin(), mat[K-1].end());
    return linear_req(mat, seed, n+1-X.size(), MOD);
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    ll n,m; cin>>n>>m;
    assert(n>=m);
    string s; cin>>s;
    cout << solve(n, s) << '\n';
}

Test details

Test 1

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`1 1 a` view save

correct output
`1` view save

user output
`1` view save

Test 2

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 20 ssxfykmuzljmwgyvldnu` view save

correct output
`1` view save

user output
`1` view save

Test 3

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 aaaaaaaaaa` view save

correct output
`1` view save

user output
`1` view save

Test 4

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 aabbbaaaab` view save

correct output
`1532` view save

user output
`1532` view save

Test 5

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 aabbacbdca` view save

correct output
`1542` view save

user output
`1542` view save

Test 6

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 ztknszhrby` view save

correct output
`3261` view save

user output
`3261` view save

Test 7

Group: 1, 2, 3, 4, 5

Verdict: WRONG ANSWER

input
`20 1 a` view save

correct output
`1` view save

user output
`758911393` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "758911393"

Test 8

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 aabbbbbbba` view save

correct output
`1689` view save

user output
`1689` view save

Test 9

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 8 abxabyab` view save

correct output
`8619` view save

user output
`8619` view save

Test 10

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

input
`20 10 ababababab` view save

correct output
`509` view save

user output
`509` view save

Test 11

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...` view save

correct output
`1` view save

user output
`1` view save

Test 12

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 bbaaabbbbbabbbbabababababbbaab...` view save

correct output
`511493117` view save

user output
`511493117` view save

Test 13

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 addabbbbbadddccadcabaacbbbaabd...` view save

correct output
`618572722` view save

user output
`618572722` view save

Test 14

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 rrdumiqrjewanjplbyvkaytbcyzbyl...` view save

correct output
`35126431` view save

user output
`35126431` view save

Test 15

Group: 2, 3, 4, 5

Verdict: WRONG ANSWER

input
`100 1 a` view save

correct output
`1` view save

user output
`962916014` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "962916014"

Test 16

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 aabbbbbbbbbbbbbbbbbbbbbbbbbbbb...` view save

correct output
`460606355` view save

user output
`460606355` view save

Test 17

Group: 2, 3, 4, 5

Verdict: WRONG ANSWER

input
`100 23 aybabtuxaybabtuyaybabtu` view save

correct output
`342213037` view save

user output
`462895168` view save

Feedback: Incorrect character on line 1 col 1: expected "342213037", got "462895168"

Test 18

Group: 2, 3, 4, 5

Verdict: ACCEPTED

input
`100 50 ababababababababababababababab...` view save

correct output
`775006564` view save

user output
`775006564` view save

Test 19

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...` view save

correct output
`1` view save

user output
`955328477` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "955328477"

Test 20

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 bbabaabbabbbaaaaaaaaaababaabbb...` view save

correct output
`911592620` view save

user output
`748088724` view save

Feedback: Incorrect character on line 1 col 1: expected "911592620", got "748088724"

Test 21

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 cacabdddcbdadabdcbdddbdddbaccb...` view save

correct output
`12869296` view save

user output
`758145439` view save

Feedback: Incorrect character on line 1 col 1: expected "12869296", got "758145439"

Test 22

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 tqoyadbshyehwcwaxbtbsqtaswkyet...` view save

correct output
`741984969` view save

user output
`328967865` view save

Feedback: Incorrect character on line 1 col 1: expected "741984969", got "328967865"

Test 23

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 1 a` view save

correct output
`1` view save

user output
`538486918` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "538486918"

Test 24

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 aabbbbbbbbbbbbbbbbbbbbbbbbbbbb...` view save

correct output
`599950419` view save

user output
`901679773` view save

Feedback: Incorrect character on line 1 col 1: expected "599950419", got "901679773"

Test 25

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 23 aybabtuxaybabtuyaybabtu` view save

correct output
`548809016` view save

user output
`300085475` view save

Feedback: Incorrect character on line 1 col 1: expected "548809016", got "300085475"

Test 26

Group: 3, 4, 5

Verdict: WRONG ANSWER

input
`1000 50 ababababababababababababababab...` view save

correct output
`765799780` view save

user output
`105453500` view save

Feedback: Incorrect character on line 1 col 1: expected "765799780", got "105453500"

Test 27

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...` view save

correct output
`1` view save

user output
`498619992` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "498619992"

Test 28

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 bbaababbaaabbabababbaaaaaabbaa...` view save

correct output
`514073453` view save

user output
`870367532` view save

Feedback: Incorrect character on line 1 col 1: expected "514073453", got "870367532"

Test 29

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 aabccabbbbabccabcdcdadbcdccdac...` view save

correct output
`438094288` view save

user output
`518717810` view save

Feedback: Incorrect character on line 1 col 1: expected "438094288", got "518717810"

Test 30

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 yzfzimxrxfukhlkrtaylohyuqkupsn...` view save

correct output
`905445077` view save

user output
`418587464` view save

Feedback: Incorrect character on line 1 col 1: expected "905445077", got "418587464"

Test 31

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 1 a` view save

correct output
`1` view save

user output
`558619508` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "558619508"

Test 32

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 aabbbbbbbbbbbbbbbbbbbbbbbbbbbb...` view save

correct output
`280596224` view save

user output
`21701558` view save

Feedback: Incorrect character on line 1 col 2: expected "280596224", got "21701558"

Test 33

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 23 aybabtuxaybabtuyaybabtu` view save

correct output
`268144314` view save

user output
`366448859` view save

Feedback: Incorrect character on line 1 col 1: expected "268144314", got "366448859"

Test 34

Group: 4, 5

Verdict: WRONG ANSWER

input
`1000000 50 ababababababababababababababab...` view save

correct output
`655244665` view save

user output
`186306248` view save

Feedback: Incorrect character on line 1 col 1: expected "655244665", got "186306248"

Test 35

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa...` view save

correct output
`1` view save

user output
`825344932` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "825344932"

Test 36

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 abbbaabbaaaaabbbbabbabbaaaaaba...` view save

correct output
`911059863` view save

user output
`107116897` view save

Feedback: Incorrect character on line 1 col 1: expected "911059863", got "107116897"

Test 37

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 cbabbcaadabbcabbdbdabbbcccbdca...` view save

correct output
`994268014` view save

user output
`162697385` view save

Feedback: Incorrect character on line 1 col 1: expected "994268014", got "162697385"

Test 38

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 pehyicejeninplaczwezhahmbhwfwi...` view save

correct output
`837165971` view save

user output
`55659218` view save

Feedback: Incorrect character on line 1 col 1: expected "837165971", got "55659218"

Test 39

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 1 a` view save

correct output
`1` view save

user output
`740562051` view save

Feedback: Incorrect character on line 1 col 1: expected "1", got "740562051"

Test 40

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 aabbbbbbbbbbbbbbbbbbbbbbbbbbbb...` view save

correct output
`114333489` view save

user output
`128307413` view save

Feedback: Incorrect character on line 1 col 2: expected "114333489", got "128307413"

Test 41

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 23 aybabtuxaybabtuyaybabtu` view save

correct output
`628064772` view save

user output
`168991881` view save

Feedback: Incorrect character on line 1 col 1: expected "628064772", got "168991881"

Test 42

Group: 5

Verdict: WRONG ANSWER

input
`1000000000 50 ababababababababababababababab...` view save

correct output
`802946327` view save

user output
`275244705` view save

Feedback: Incorrect character on line 1 col 1: expected "802946327", got "275244705"

Putka Open 2025 – 4/5

Merkkijonot

Code

Test details

Test 1

Test 2

Test 3

Test 4

Test 5

Test 6

Test 7

Test 8

Test 9

Test 10

Test 11

Test 12

Test 13

Test 14

Test 15

Test 16

Test 17

Test 18

Test 19

Test 20

Test 21

Test 22

Test 23

Test 24

Test 25

Test 26

Test 27

Test 28

Test 29

Test 30

Test 31

Test 32

Test 33

Test 34

Test 35

Test 36

Test 37

Test 38

Test 39

Test 40

Test 41

Test 42

Tasks

Submissions (jlaire)