Submission #522862

#	Time	Username	Problem	Language	Result	Execution time	Memory
522862		acm	Bigger segments (IZhO19_segments)	C++14	100 / 100	250 ms	29108 KiB

segments

#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#endif
#include <bits/stdc++.h>
#define speed                   \
  ios_base::sync_with_stdio(0); \
  cin.tie(0);                   \
  cout.tie(0);
#define precision     \
  cout.precision(30); \
  cerr.precision(10);
#define ll long long
#define ld long double
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define mp(x, y) make_pair(x, y)
#define all(x) x.begin(), x.end()
#define pc(x) __builtin_popcount(x)
#define pcll(x) __builtin_popcountll(x)
#define F first
#define S second
using namespace std;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void ioi(string name) {
  freopen((name + ".in").c_str(), "r", stdin);
  freopen((name + ".out").c_str(), "w", stdout);
}
ll n, a[500005], b[500005], t[2000005];
pair<ll, ll> dp[500005];
void upd(ll v, ll l, ll r, ll x, ll y) {
  if (l == r) {
    t[v] = y;
    return;
  }
  ll tm = (l + r) / 2;
  if (x <= tm)
    upd(v + v, l, tm, x, y);
  else
    upd(v + v + 1, tm + 1, r, x, y);
  t[v] = min(t[v + v], t[v + v + 1]);
}
ll get(ll v, ll l, ll r, ll x) {
  if (t[v] > x) return 0;
  if (l == r) return l;
  ll tm = (l + r) / 2;
  if (t[v + v + 1] <= x)
    return get(v + v + 1, tm + 1, r, x);
  else
    return get(v + v, l, tm, x);
}
int main() {
  speed;
  precision;
  // code
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    b[i] = b[i - 1] + a[i];
    dp[i] = mp(0, (1LL << 60));
    upd(1, 1, n, i, dp[i].S);
  }
  for (int i = 1; i <= n; i++) {
    // b[z] - b[y] >= b[y] - b[x]
    // b[z] >= 2b[y] - b[x]
    ll x = get(1, 1, n, b[i]);
    dp[i] = mp(dp[x].F + 1, b[i] + b[i] - b[x]);
    upd(1, 1, n, i, dp[i].S);
  }
  cout << dp[n].F;
  // endl
#ifndef ONLINE_JUDGE
  cerr << "\nTime elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
  return 0;
}

Compilation message (stderr)

segments.cpp: In function 'void ioi(std::string)':
segments.cpp:26:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |   freopen((name + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
segments.cpp:27:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |   freopen((name + ".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