Submission #752059

#	Time	Username	Problem	Language	Result	Execution time	Memory
752059		Stickfish	Table Tennis (info1cup20_tabletennis)	C++17	100 / 100	578 ms	42996 KiB

tabletennis

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

const int MAXN = 157000;

int get_bestval(vector<int> a, int k) {
    int n = a.size();
    map<int, int> mp;
    for (int i = 0; i < n; ++i) {
        int ctr = n - i - 1;
        for (int t = -k; t <= k; ++t) {
            if (ctr + t <= i || ctr + t >= n)
                continue;
            int val = a[i] + a[ctr + t];
            ++mp[val];
        }
    }
    int mxval = 0;
    int mxcnt = 0;
    for (auto [val, cnt] : mp) {
        if (mxcnt < cnt) {
            mxval = val;
            mxcnt = cnt;
        }
    }
    return mxval;
}

vector<int> get_withsum(vector<int> a, int sm) {
    int n = a.size();
    int j = n - 1;
    vector<int> ans;
    for (int i = 0; i < n; ++i) {
        while (j > i && a[i] + a[j] > sm)
            --j;
        if (a[i] + a[j] == sm) {
            ans.push_back(a[i]);
            ans.push_back(a[j]);
        }
    }
    return ans;
}

void solve_slow(vector<int> a, int n, int k) {
    int mxval = get_bestval(a, k);
    vector<int> ans = get_withsum(a, mxval);
    while (ans.size() > n)
        ans.pop_back();
    sort(ans.begin(), ans.end());
    for (int i = 0; i < n; ++i) {
        cout << ans[i] << ' ';
    }
    cout << '\n';
}

const ll MOD = 1000000007;

ll pw(ll a, ll m) {
    if (!m)
        return 1;
    a %= MOD;
    if (m % 2)
        return a * pw(a, m - 1) % MOD;
    return pw(a * a, m / 2);
}

void solve_smallk(vector<int> a, int n, int k) {
    int m = n + k;
    vector<int> na;
    for (int i = 0; i < 3 * k; ++i)
        na.push_back(a[i]);
    for (int i = m - 3 * k; i < m; ++i)
        na.push_back(a[i]);
    int mxval = get_bestval(na, k);
    vector<int> ans = get_withsum(a, mxval);
    while (ans.size() > n)
        ans.pop_back();
    assert(ans.size() == n);
    sort(ans.begin(), ans.end());
    for (int i = 0; i < n; ++i) {
        cout << ans[i] << ' ';
    }
    cout << '\n';
    return;

    vector<int> dif(m - 1);
    for (int i = 0; i + 1 < n + k; ++i) {
        dif[i] = a[i + 1] - a[i];
    }
    vector<ll> phash_(m);
    vector<ll> rhash_(m);
    vector<ll>::iterator phash = phash_.begin() + 1;
    vector<ll>::iterator rhash = rhash_.begin() + 1;
    for (int i = 0; i + 1 < m; ++i) {
        phash[i] = (phash[i - 1] + pw(101, i) * dif[i]) % MOD;
        rhash[i] = (rhash[i - 1] + pw(101, i) * dif[m - 2 - i]) % MOD;
    }
    int lb = 1, ub = n / 2 + 1;
    while (ub - lb > 1) {
        int mb = (lb + ub) / 2;
        set<ll> hashes;
        for (int i = 0; i + mb < m - 1; ++i) {
            ll hsh = (phash[i + mb] - phash[i - 1]) / pw(101, MOD - 1 - i);
            hashes.insert(hsh);
            //hashes.push_back(
        }

    }
}

signed main() {
    int n, k;
    cin >> n >> k;
    vector<int> a(n + k);
    for (int i = 0; i < n + k; ++i) {
        cin >> a[i];
    }
    if (n * k <= 1000000) {
        solve_slow(a, n, k);
        return 0;
    } else {
        solve_smallk(a, n, k);
        return 0;
    }
}

Compilation message (stderr)

tabletennis.cpp: In function 'void solve_slow(std::vector<int>, int, int)':
tabletennis.cpp:53:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   53 |     while (ans.size() > n)
      |            ~~~~~~~~~~~^~~
tabletennis.cpp: In function 'void solve_smallk(std::vector<int>, int, int)':
tabletennis.cpp:82:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   82 |     while (ans.size() > n)
      |            ~~~~~~~~~~~^~~
In file included from /usr/include/c++/10/cassert:44,
                 from tabletennis.cpp:5:
tabletennis.cpp:84:23: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   84 |     assert(ans.size() == n);
      |            ~~~~~~~~~~~^~~~

• Subtask 1: 11 / 11
• Subtask 2: 9 / 9
• Subtask 3: 14 / 14
• Subtask 4: 15 / 15
• Subtask 5: 9 / 9
• Subtask 6: 14 / 14
• Subtask 7: 15 / 15
• Subtask 8: 13 / 13