Submission #336881

#	Time	Username	Problem	Language	Result	Execution time	Memory
336881		boykut	Bigger segments (IZhO19_segments)	C++14	27 / 100	105 ms	1516 KiB

segments

#include <bits/stdc++.h>

using namespace std;

int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  
  vector < int > a(n);
  
  for (int & to : a) {
    cin >> to;
  }
  
  vector < int64_t > prefsum(n);
  for (int i = 0; i < n; i++) {
    prefsum[i] = a[i];
    if (i)
      prefsum[i] += prefsum[i - 1];
  }
  
  auto get = [&] (int left, int right) -> int64_t {
    return prefsum[right] - (left == 0 ? 0ll : prefsum[left - 1]);
  };
  
  /*if (n <= 500) {
    set < pair < int64_t, int > > dp[n];
    
    for (int i = 0; i < n; i++) {
      dp[i].insert(make_pair(get(0, i), 1));
    }
    
    for (int i = 0; i < n; i++) {
      for (int j = 1; j <= i; j++) {
        int mx = -1;
        for (auto it : dp[j - 1]) {
          if (it.first <= get(j, i)) {
            if (mx == -1 || it.second > mx)
              mx = it.second;
          }
        }
        if (mx == -1) continue;
        dp[i].insert(make_pair(get(j, i), mx + 1));
      }
    }
    
    int mx = 0;
    for (auto it : dp[n - 1]) {
      if (it.second > mx)
        mx = it.second;
    }
    cout << mx << '\n';
    return 0;
  }*/
  if (n <= 600) {
    vector < vector < bool > > can(n, vector < bool > (n, false));
    vector < vector < int > > dp(n, vector < int > (n, 0));
    
    for (int i = 0; i < n; i++) {
      can[0][i] = true;
      dp[0][i] = 1;
    }
    
    for (int i = 0; i < n; i++) {
      for (int j = 0; j <= i; j++) {
        for (int k = 0; k <= j - 1; k++) {
          if (get(k, j - 1) <= get(j, i) && can[k][j - 1]) {
            dp[j][i] = max(dp[j][i], dp[k][j - 1] + 1);
            can[j][i] = true;
          }
        }
      }
    }
    
    int mx = 0;
    for (int i = 0; i < n; i++) {
      mx = max(mx, dp[i][n - 1]);
    }
    cout << mx << '\n';
    return 0;
  }
  return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27