Submission #952590

#	Time	Username	Problem	Language	Result	Execution time	Memory
952590		nguyennh	Divide and conquer (IZhO14_divide)	C++14	100 / 100	41 ms	8636 KiB

divide

#include<bits/stdc++.h>
#define el '\n'
using namespace std ;

const int MN = 1e5 + 6;
const int64_t inf = 1e18;

int x[MN] , g[MN] , d[MN] , n;

namespace sub_trau{
  void solve(){
    int64_t ans = 0;
    vector<int64_t> pref_gold(n + 5) , pref_en(n + 5);
    for ( int i = 1 ; i <= n ; i++ ){
      pref_gold[i] = pref_gold[i - 1] + g[i];
      pref_en[i] = pref_en[i - 1] + d[i];
    }
    for ( int i = 1 ; i <= n ; i++ ){
      for ( int j = i ; j <= n ; j++ ){
        if (pref_en[j] - pref_en[i - 1] >= x[j] - x[i]) ans = max(ans , pref_gold[j] - pref_gold[i - 1]);
      }
    }
    cout << ans;
  }
}

namespace sub_final{
  struct Segtri{
    vector<int64_t> st;
    
    Segtri(int n) : st(4 * n + 5) {
      for ( int i = 1 ; i <= n ; i++ ) st[i] = inf;
    }
    
    void update(int id , int l , int r , int i , int64_t val){
      if (i < l || i > r) return;
      if (l == r){
        st[id] = val;
        return;
      }
      int mid = l + r >> 1;
      update(id << 1 , l , mid , i , val);
      update(id << 1 | 1 , mid + 1 , r , i , val);
      st[id] = min(st[id << 1] , st[id << 1 | 1]);
    }
    
    int walk(int id , int l , int r , int64_t x){
      if (l == r) return l;
      int mid = l + r >> 1;
      if (st[id << 1] <= x) return walk(id << 1 , l , mid , x);
      return walk(id << 1 | 1 , mid + 1 , r , x);
    }
  };
  
  void solve(){
    vector<int64_t> pref(n + 5) , f(n + 5);
    for ( int i = 1 ; i <= n ; i++ ){
      pref[i] = pref[i - 1] + g[i];
      f[i] = f[i - 1] + d[i];
    }
    Segtri it(n);
    for ( int i = 1 ; i <= n ; i++ ) it.update(1 , 1 , n , i , f[i] - x[i] - d[i]);
    int64_t ans = 0;
    for ( int i = 1 ; i <= n ; i++ ){
      int pos = it.walk(1 , 1 , n , f[i] - x[i]);
      ans = max(ans , pref[i] - pref[pos - 1]);
    }
    cout << ans;
  }
}

int32_t main (){
//  freopen("divide.inp" , "r" , stdin);
//  freopen("divide.out" , "w" , stdout);
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for ( int i = 1 ; i <= n ; i++ ) cin >> x[i] >> g[i] >> d[i];
  if (n <= 5000){
    sub_trau::solve();
    return 0;
  }
  sub_final::solve();
}

Compilation message (stderr)

divide.cpp: In member function 'void sub_final::Segtri::update(int, int, int, int, int64_t)':
divide.cpp:41:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   41 |       int mid = l + r >> 1;
      |                 ~~^~~
divide.cpp: In member function 'int sub_final::Segtri::walk(int, int, int, int64_t)':
divide.cpp:49:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   49 |       int mid = l + r >> 1;
      |                 ~~^~~

• Subtask 1: 17 / 17
• Subtask 2: 31 / 31
• Subtask 3: 52 / 52