Submission #497381

#	Time	Username	Problem	Language	Result	Execution time	Memory
497381		xynex	Bigger segments (IZhO19_segments)	C++17	100 / 100	74 ms	20836 KiB

segments

/*
* Author: xynex
* Created: 23.12.2021 09:18
* 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 = 3e6 + 5;
const ll INF = 9e18;
const int M = 3e3 + 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 a[N], pref[N], dp[N], mx[N];
int n;
void solve() {
    read(n);
    //Govno code Let's goooo.
    for(int i = 1; i <= n; ++i) read(a[i]), pref[i] = pref[i - 1] + a[i];
    pref[n + 1] = INF;
    for(int i = 1; i <= n; ++i) {
        mx[i] = max(mx[i], mx[i - 1]);
        dp[i] = dp[mx[i]] + 1;
        ll cur = pref[i] * 2 - pref[mx[i]];
        int l = i + 1, r = n;
        while((r - l) >= 0) {
            int mid = (r + l) >> 1;
            if(pref[i] * 2 <= (pref[mid] + pref[mx[i]])) r = mid - 1;
            else l = mid + 1;
        }
        mx[l] = max(mx[l], i * 1ll);
    }
    //Psmlya
    //for(int i = 1; i <= n; ++i) write(mx[i], ' ');
    print(dp[n]);
}

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)

segments.cpp: In function 'void solve()':
segments.cpp:103:12: warning: unused variable 'cur' [-Wunused-variable]
  103 |         ll cur = pref[i] * 2 - pref[mx[i]];
      |            ^~~
segments.cpp: In function 'void freop(std::string)':
segments.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);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
segments.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: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 36 / 36
• Subtask 5: 27 / 27