Language: C++

#pragma GCC optimize("O3", "unroll-loops")
#pragma GCC target("avx")
#include <algorithm>
#include <array>
#include <chrono>
#include <iostream>
#include <vector>
#include <random>
using namespace std;
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template <typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template <typename V, typename T> void ndfill(V &x, const T &val) { x = val; }
template <typename V, typename T> void ndfill(vector<V> &vec, const T &val) { for (auto &v : vec) ndfill(v, val); }
template <typename T> bool chmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template <typename T> bool chmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template <typename T> istream &operator>>(istream &is, vector<T> &vec) { for (auto &v : vec) is >> v; return is; }
template <typename T> ostream &operator<<(ostream &os, const vector<T> &vec) { os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;

constexpr int Z = 26;
int D;
array<int, Z> C;
vector<vector<int>> S;

vector<int> schedule;
vector<vector<int>> prv, nxt;
int current_score;


vector<int> calc_score()
{
    vector<int> last(26, 0);
    vector<int> ret;
    FOR(d, 1, schedule.size())
    {
        current_score += S[d][schedule[d]];
        last[schedule[d]] = d;
        prv[d + 1][schedule[d]] = d;
        nxt[d - 1][schedule[d]] = d;
        REP(i, Z) current_score -= C[i] * (d - last[i]);
        ret.emplace_back(current_score);
    }
    REP(d, schedule.size()) REP(i, Z) chmax(prv[d + 1][i], prv[d][i]);
    IREP(d, schedule.size()) REP(i, Z) chmin(nxt[d][i], nxt[d + 1][i]);
    return ret;
}

void modify(int day, int contest)
{
    int cold = schedule[day];
    if (cold == contest) return;

    int dprv = prv[day][cold], dnxt = nxt[day][cold];
    nxt[dprv][cold] = dnxt;
    prv[dnxt][cold] = dprv;
    FOR(d, dprv + 1, dnxt) nxt[d][cold] = dnxt, prv[d][cold] = dprv;

    current_score -= C[cold] * (day - dprv) * (dnxt - day) + S[day][cold];

    schedule[day] = contest;

    dprv = prv[day][contest], dnxt = nxt[day][contest];
    nxt[day][contest] = dnxt, prv[day][contest] = dprv;

    FOR(d, dprv, day) nxt[d][contest] = day;
    FOR(d, day + 1, dnxt + 1) prv[d][contest] = day;

    current_score += C[contest] * (day - dprv) * (dnxt - day) + S[day][contest];
}

uint32_t rand_int() // XorShift random integer generator
{
    static uint32_t x = 123456789, y = 362436069, z = 521288629, w = 88675123;
    uint32_t t = x ^ (x << 11);
    x = y;
    y = z;
    z = w;
    return w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
}

struct rand_int_
{
    using lint = long long;
    mt19937 mt;
    rand_int_() : mt(chrono::steady_clock::now().time_since_epoch().count()) {}
    lint operator()(lint x) { return this->operator()(0, x); } // [0, x)
    lint operator()(lint l, lint r)
    {
        uniform_int_distribution<lint> d(l, r - 1);
        return d(mt);
    }
} rnd;

void output()
{
    FOR(i, 1, schedule.size())
    {
        cout << schedule[i] + 1 << '\n';
    }
    exit(0);
}
int main()
{
    auto START = std::chrono::system_clock::now();

    cin >> D;
    REP(i, Z) cin >> C[i];
    S.resize(D + 1);
    ndarray(S, D + 1, Z);
    REP(d, D) REP(i, Z) cin >> S[d + 1][i];

    ndarray(prv, D + 2, Z);
    ndfill(prv, 0);
    ndarray(nxt, D + 2, Z);
    ndfill(nxt, D + 1);

    schedule.resize(D + 1);
    FOR(d, 1, D + 1)
    {
        schedule[d] = max_element(S[d].begin(), S[d].end()) - S[d].begin();
    }
    calc_score();

    // output();
    // modify(day, q) day: 1-indexed, 0<=q<26
    vector<int> jun(D);
    iota(ALL(jun), 1);

    int cnt = 0;
    while (true)
    {
        cnt++;
        if (rand_int() % 20 == 0)
        {
            random_shuffle(ALL(jun), rnd);
            for (auto d : jun)
            {
                int h = current_score, argh = schedule[d];
                REP(i, Z)
                {
                    modify(d, i);
                    if (chmax(h, current_score))
                        argh = i;
                }
                modify(d, argh);
            }
        }
        else
        {
            int d = rand_int() % (D - 1) + 1;
            int e = d + rand_int() % min(D - d, 20) + 1;
            int sd = schedule[d], se = schedule[e];

            int h = current_score;
            modify(d, se);
            modify(e, sd);
            if (chmax(h, current_score))
            {
            }
            else
            {
                modify(d, sd);
                modify(e, se);
            }
        }

        if (chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now() - START).count() > 1990)
        {
            dbg(cnt);
            dbg(current_score);
            output();
            cout << current_score << '\n';
            exit(0);
        }
    }
}


Compiler output:
a.cc: In function 'int main()':
a.cc:141:27: warning: 'void std::random_shuffle(_RAIter, _RAIter, _Generator&&) [with _RAIter = __gnu_cxx::__normal_iterator<int*, vector<int> >; _Generator = rand_int_&]' is deprecated: use 'std::shuffle' instead [-Wdeprecated-declarations]
  141 |             random_shuffle(ALL(jun), rnd);
      |             ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:4531:5: note: declared here
 4531 |     random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
      |     ^~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:43,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:6:
/usr/include/c++/14/bits/allocator.h: In destructor 'std::_Vector_base<std::vector<int>, std::allocator<std::vector<int> > >::_Vector_impl::~_Vector_impl()':
/usr/include/c++/14/bits/allocator.h:182:7: error: inlining failed in call to 'always_inline' 'std::allocator< <template-parameter-1-1> >::~allocator() noexcept [with _Tp = std::vector<int>]': target specific option mismatch
  182 |       ~allocator() _GLIBCXX_NOTHROW { }
      |       ^
In file included from /usr/include/c++/14/vector:66,
                 from a.cc:7:
/usr/include/c++/14/bits/stl_vector.h:132:14: note: called from here
  132 |       struct _Vector_impl
      |              ^~~~~~~~~~~~