Submission #777814

#	Time	Username	Problem	Language	Result	Execution time	Memory
777814		epicci23	Bigger segments (IZhO19_segments)	C++17	100 / 100	89 ms	44256 KiB

segments

#include "bits/stdc++.h"
#pragma optimize ("Bismillahirrahmanirrahim")
using namespace std;
#define pb push_back
#define ff first
#define ss second
#define endl "\n" 
#define int long long
#define double long double
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define what_is(x) cerr << #x << " is " << x << endl;
//#define m (l+r)/2
constexpr int N=200005;
constexpr int MOD=1000000007;
constexpr int  INF2 = LLONG_MAX;
constexpr int INF=(int)1e18;
constexpr int LOG=30;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
typedef priority_queue<pii,vector<pii>,greater<pii>> min_pq;
typedef priority_queue<pii> max_pq;
typedef long long ll;
//to think//
/*
 * graph approach
 * dp
 * dividing the problem to smaller statements
 * finding the real constraint
 * sqrt decomposition
 * greedy approach
 * pigeonhole principle
 * rewriting the problem/equality 
 * bitwise approaches
 * binary search if monotonic
 * divide and conquer
 * combinatorics
 * inclusion - exclusion
 * think like bfs
*/



inline int in()
{
  int x;cin >> x;
  return x;
}

inline string in2()
{
  string x;cin >> x;
  return x;
}


void solve()
{
  int n=in();
  int ar[n+1];
  for(int i=1;i<=n;i++) ar[i]=in();

  int pre[n+1]; pre[0]=0;
  for(int i=1;i<=n;i++) pre[i]=ar[i]+pre[i-1];

  vector<pii> dp[n+2];
  
  int dp2[n+2];
  for(int i=0;i<=n;i++) dp2[i]=INF;

  dp2[0]=0;
  dp[0].pb({0,0});

  auto get=[&](int l,int r)
  {
    if(l>r) return -INF;
    return pre[r]-pre[l-1];
  };

  for(int i=1;i<=n;i++)
  {
    int l=0,r=i-1;
    while(l<r)
    {
      int mid=(l+r+1)/2;
      if(!dp[mid].empty() && dp2[mid]<=pre[i]) l=mid;
      else r=mid-1;
    }
    int x=l;
    r=sz(dp[x])-1;
    l=0;
    
    while(l<r)
    {
      int mid=(l+r+1)/2;
      if(dp[x][mid].ff<=pre[i]) l=mid;
      else r=mid-1;
    }
    
    //cout << "i: " << i << endl;
    //cout << x+1 << " " << dp[x][l].ss+1 << " " << i <<  endl;
    
    while(!dp[x+1].empty() && dp[x+1].back().ff>=get(dp[x][l].ss+1,i)+pre[i]) dp[x+1].pop_back();
    dp[x+1].pb({get(dp[x][l].ss+1,i)+pre[i],i});
    dp2[x+1]=min(dp2[x+1],pre[i]+get(dp[x][l].ss+1,i));
  } 
  

  for(int i=n;i>=0;i--)
  {
    if(!dp[i].empty())
    {
      cout << i << endl;
      return;
    }
  }
}

int32_t main(){
   

     cin.tie(0); ios::sync_with_stdio(0);
     cout << fixed <<  setprecision(15);
   
   int t=1;//cin>> t;
 
 for(int i=1;i<=t;i++)
 {
  //  cout << "Case #" << i << ": ";
    solve();
 }
 
 return 0;
}

Compilation message (stderr)

segments.cpp:2: warning: ignoring '#pragma optimize ' [-Wunknown-pragmas]
    2 | #pragma optimize ("Bismillahirrahmanirrahim")
      |

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