Submission #257648

#	Time	Username	Problem	Language	Result	Execution time	Memory
257648		BThero	Bigger segments (IZhO19_segments)	C++17	100 / 100	207 ms	25080 KiB

segments

// chrono::system_clock::now().time_since_epoch().count()
#include<bits/stdc++.h>

#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << #x << " = " << x << endl;

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int MAXN = (int)5e5 + 5;
const ll INF = (ll)1e16;

pair<int, ll> dp[MAXN];
ll t[MAXN << 2];
ll pref[MAXN];
int arr[MAXN];
int n;

void build(int v, int tl, int tr) {
  if (tl == tr) {
    t[v] = INF;
    return;
  }
  
  int mid = (tl + tr) >> 1;
  int c1 = (v << 1), c2 = (c1 | 1);
  
  build(c1, tl, mid);
  build(c2, mid + 1, tr);
  
  t[v] = min(t[c1], t[c2]);
}

void update(int v, int tl, int tr, int p, ll x) {
  if (tl == tr) {
    t[v] = x;
    return;
  }
  
  int mid = (tl + tr) >> 1;
  int c1 = (v << 1), c2 = (c1 | 1);
  
  if (p <= mid) {
    update(c1, tl, mid, p, x);
  }
  else {
    update(c2, mid + 1, tr, p, x);
  }
  
  t[v] = min(t[c1], t[c2]);
}

int query(int v, int tl, int tr, ll lim) {
  if (tl == tr) {
    return tl;
  }
  
  int mid = (tl + tr) >> 1;
  int c1 = (v << 1), c2 = (c1 | 1);
  
  if (t[c2] <= lim) {
    return query(c2, mid + 1, tr, lim);
  }
  else {
    return query(c1, tl, mid, lim);
  }
}

void solve() {
  scanf("%d", &n);
  
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &arr[i]);
    pref[i] = pref[i - 1] + arr[i];
  }
  
  for (int i = 1; i <= n; ++i) {
    dp[i] = mp(0, INF);
  }
  
  dp[0] = mp(0, 0);
  build(1, 0, n);
  update(1, 0, n, 0, 0);
    
  for (int i = 1; i <= n; ++i) {
    int j = query(1, 0, n, pref[i]);
    dp[i].fi = dp[j].fi + 1;
    dp[i].se = pref[i] - pref[j];
    update(1, 0, n, i, dp[i].se + pref[i]);
  }
  
  printf("%d\n", dp[n].fi);
}

int main() {
  int tt = 1;
  
  while (tt--) {
    solve();
  }

  return 0;
}

Compilation message (stderr)

segments.cpp: In function 'void solve()':
segments.cpp:77:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &n);
   ~~~~~^~~~~~~~~~
segments.cpp:80:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &arr[i]);
     ~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 36 / 36
• Subtask 5: 27 / 27