Submission #693089

#	Time	Username	Problem	Language	Result	Execution time	Memory
693089		taher	Bigger segments (IZhO19_segments)	C++17	100 / 100	77 ms	27208 KiB

segments

#include <bits/stdc++.h>

using namespace std;

vector<array<long long, 2>> cur;
int id = -1;

void Insert(long long v, int j) {
  // keep the whole thing strictly increasing
  while (!cur.empty() && cur.back()[0] >= v) {
    cur.pop_back();
  }
  cur.push_back({v, j});
  return ;
}

int Query(long long v) {
  while (id + 1 < (int) cur.size() && v >= cur[id + 1][0]) {
    ++id;
  }
  if (id >= 0) {
    return cur[id][1];
  }
  return -1;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<long long> pref(a.begin(), a.end());
  for (int i = 1; i < n; i++) {
    pref[i] += pref[i - 1];
  }
  vector<array<long long, 2>> dp(n);
  dp[0] = {1, a[0]};
  Insert(2LL * a[0], 0);
  for (int i = 1; i < n; i++) {
    dp[i] = dp[i - 1];
    dp[i][1] += a[i];
    int pos = Query(pref[i]);
    if (pos >= 0) {
      if (dp[i][0] < dp[pos][0] + 1) {
        dp[i][0] = dp[pos][0] + 1;
        dp[i][1] = pref[i] - pref[pos];
      } else if (dp[i][0] == dp[pos][0] + 1) {
        dp[i][1] = min(dp[i][1], pref[i] - pref[pos]);
      }
    }
    Insert(dp[i][1] + pref[i], i);
  }
  cout << dp[n - 1][0] << '\n';
  return 0; 
}

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