Submission #498466

#	Time	Username	Problem	Language	Result	Execution time	Memory
498466		xynex	Split the sequence (APIO14_sequence)	C++17	71 / 100	61 ms	131076 KiB

sequence

/*
* Author: xynex
* Created: 25.12.2021 14:00
* Why am I so stupid? :c
* Slishkom slab
*/

#include <bits/stdc++.h>

// #pragma GCC optimize("inline")
// #pragma GCC optimize("-fgcse,-fgcse-lm")
// #pragma GCC optimize("-ftree-pre,-ftree-vrp")
// #pragma GCC optimize("-ffast-math")
// #pragma GCC optimize("-fipa-sra")
// #pragma GCC optimize("-fpeephole2")
// #pragma GCC optimize("-fsched-spec")
// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
// #pragma GCC optimize("unroll-loops")

using namespace std;

#define ll long long
#define dl double long
#define ull unsigned long long
#define pr pair
#define vt vector
#define ff first
#define ss second
#define mp make_pair
#define sz(a) (int)a.size()
#define pb push_back
#define pf push_front
#define popB pop_back
#define popF pop_front
#define bit_count __builtin_popcount
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sp(x) fixed << setprecision(x)

template<typename T> T get_rand(T l, T r) {
    random_device rd;
    mt19937 gen(rd());
    return uniform_int_distribution<T>(l, r)(gen);
}

template<typename T> T lcm(T a, T b) { return a * (b / __gcd(a, b)); }

template<class A> void read(vt<A>& v);
template<class A, size_t S> void read(array<A, S>& a);
template<class T> void read(T& x) { cin >> x; }
void read(double& d) { string t; read(t); d = stod(t); }
void read(long double& d) { string t; read(t); d = stold(t); }
template<class H, class... T> void read(H& h, T&... t) { read(h); read(t...); }
template<class A> void read(vt<A>& x) { for (auto& a : x) read(a); }
template<class A, size_t S> void read(array<A, S>& x) { for (auto& a : x) read(a); }

string to_string(char c) { return string(1, c); }
string to_string(bool b) { return b ? "true" : "false"; }
string to_string(const char* s) { return string(s); }
string to_string(string s) { return s; }
string to_string(vt<bool> v) { string res; for (int i = 0; i < sz(v); ++i) res += char('0' + v[i]); return res; }
template<size_t S> string to_string(bitset<S> b) { string res; for (int i = 0; i < S; ++i) res += char('0' + b[i]); return res; }
template<class T> string to_string(T v) { bool f = 1; string res; for (auto x : v) { if (!f) res += ' '; f = 0; res += to_string(x); } return res; }

template<class A> void write(A x) { cout << to_string(x); }
template<class H, class... T> void write(const H& h, const T&... t) { write(h); write(t...); }

void print() { write("\n"); }
template<class H, class... T> void print(const H& h, const T&... t) { write(h); if (sizeof...(t)) write(' '); print(t...); }

void freop(string s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const ll INF = 9e18;
const int M = 2e2 + 5;
const dl pi = acos(-1);
const dl eps = 1e-12;
const int sq = 700;

int dx[] = {-1, 0, 1, 0};
int dy[] = {0, -1, 0, 1};
/* ll vs int*/

void precalc() {

}

ll dp[N][5], a[N], pref[N], path[N][M];
int n, k;
bool get(ll x, ll y, ll z) {
    ll ind = dp[y][0] - dp[x][0];
//    print(ind);
    ll ind1 = (pref[n] - pref[z]) * (pref[y] - pref[x]);
//    print(ind1);
    return ind >= ind1;
}
bool get1(ll x, ll y, ll z) {
    ll ind = dp[y][0] - dp[x][0];
    ind *= pref[z] - pref[y];
//    print(ind);
    ll ind1 = dp[z][0] - dp[y][0];
    ind1 *= pref[y] - pref[x];
//    print(ind1);
    return ind <= ind1;
}
void solve() {
    read(n, k);
    for(int i = 1; i <= n; ++i) {
        read(a[i]);
        pref[i] = pref[i - 1] + a[i];
    }
    for(int i = 1; i <= k; ++i) {
        deque<ll> d = {0, 0};
        for(int j = 1; j <= n; ++j) {
            while(sz(d) >= 2 && get(d[0], d[1], j)) d.pop_front();
            int l = d.front();
            if(dp[l][0] + (pref[n] - pref[j]) * (pref[j] - pref[l]) >= dp[j][1]) {
                dp[j][1] = dp[l][0] + (pref[n] - pref[j]) * (pref[j] - pref[l]);
                path[j][i] = l;
            }
            while(sz(d) >= 2 && get1(d[sz(d) - 2], d[sz(d) - 1], j)) d.pop_back();
            d.push_back(j);
//            print(d);
        }
        for(int j = 1; j <= n; ++j) dp[j][0] = dp[j][1], dp[j][1] = 0;
    }
//    for(int i = 1; i <= k; ++i) {
//        print(i);
//        for(int j = 1; j <= n; ++j) write(dp[j][i], ' ');
//        print("");
//    }
    int whr = 0;
    ll mx = -INF;
    for(int i = 1; i <= n; ++i) {
        if(mx < dp[i][0]) {
            mx = dp[i][0];
            whr = i;
        }
    }
    print(mx);
    for(int i = 1; i <= k; ++i) {
        write(whr, ' ');
        whr = path[whr][k - i + 1];
    }
}

int main() {
    //freop("");
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    //read(t);
    precalc();
    for (int i = 1; i <= t; ++i) {
        //write("Case #" + to_string(i) + ": ");
        solve();
    }
    return 0;
}

Compilation message (stderr)

sequence.cpp: In function 'void freop(std::string)':
sequence.cpp:73:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |     freopen((s + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sequence.cpp:74:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |     freopen((s + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 0 / 29