Submission #701649

#	Time	Username	Problem	Language	Result	Execution time	Memory
701649		lto5	Bigger segments (IZhO19_segments)	C++14	100 / 100	79 ms	18816 KiB

segments

#include <bits/stdc++.h>

using namespace std;
using TNode = pair<int, int64_t>;

int a[500005];
int64_t s[500005];
TNode f[500005];

int64_t get(int l, int r) {
  return s[r] - s[l - 1];
}

TNode better(TNode a, TNode b) {
  if (a.first != b.first) {
    return a.first > b.first ? a : b;
  }
  return a.second < b.second ? a : b;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
#define task "a"
  if (fopen(task ".inp", "r")) {
    freopen(task ".inp", "r", stdin);
    freopen(task ".out", "w", stdout);
  }
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    s[i] = s[i - 1] + a[i];
  }
  for (int i = 0; i <= n; i++) {
    f[i] = {0, 1e18};
  }
  f[1] = {1, a[1]};
  for (int i = 1; i <= n; i++) {
    if (f[i].first == 0) {
      continue;
    }
    f[i + 1] = better(f[i + 1], {f[i].first, f[i].second + a[i + 1]});
    int lo = i + 1, hi = n;
    int pos = -1;
    while (lo <= hi) {
      int mid = (lo + hi) / 2;
      if (get(i + 1, mid) >= f[i].second) {
        pos = mid;
        hi = mid - 1;
      } else {
        lo = mid + 1;
      }
    }
    if (pos != -1) {
      f[pos] = better(f[pos], {f[i].first + 1, get(i + 1, pos)});
    }
  }
  int best = 0;
  for (int i = 1; i <= n; i++) {
    best = max(best, f[i].first);
  }
  cout << best;
  return 0;
}

Compilation message (stderr)

segments.cpp: In function 'int main()':
segments.cpp:27:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     freopen(task ".inp", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
segments.cpp:28:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |     freopen(task ".out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~

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