Submission #1206361

#	Time	Username	Problem	Language	Result	Execution time	Memory
1206361		pera	Horses (IOI15_horses)	C++20	17 / 100	267 ms	42352 KiB

horses

#include<bits/stdc++.h>
#include "horses.h"
#define LL long long
using namespace std;
const int N_MAX = 5E5 + 1;
const LL mod = 1E9 + 7;
int n;
set<int> S;
vector<int> x(N_MAX);
template<typename T>
struct segment_tree{
   vector<T> st , a;
   T neutral;
   int size;
   function<T(T , T)> join;
   segment_tree(int _size , vector<T> _a , T _neutral , function<T(T , T)> _join){
      join = _join;
      size = _size;
      neutral = _neutral;
      a = _a;
      st = vector<T>(2 * _size , _neutral);
      build();
   }
   segment_tree(int _size , T _neutral , function<T(T , T)> _join){
      join = _join;
      size = _size;
      neutral = _neutral;
      st = vector<T>(2 * _size , _neutral);
   }
   void build(){
      for(int i = 2 * size - 1;i > 0;i --){
         st[i] = (i < size ? join(st[i << 1] , st[i << 1 | 1]) : a[i - size + 1]);
      }
   }
   void point_update(int x , T val){
      --x;
      st[x + size] = join(val , st[x + size]);
      for(x += size;x > 1;x >>= 1){
         st[x >> 1] = join(st[x] , st[x ^ 1]);
      }
   }
   void point_assign(int x , T val){
      --x;
      st[x + size] = val;
      for(x += size;x > 1;x >>= 1){
         st[x >> 1] = join(st[x] , st[x ^ 1]);
      }
   }
   T range_query(int l , int r){
      if(l > r){
         return neutral;
      }
      --l;
      T resL = neutral , resR = neutral;
      for(l += size , r += size;l < r;l >>= 1 , r >>= 1){
         if(l & 1){
            resL = join(resL , st[l++]);
         }
         if(r & 1){
            resR = join(st[--r] , resR);
         }
      }
      return join(resL , resR);
   }
};
int stf(int x , int y){
   return max(x , y);
};
LL sff(LL x , LL y){
   return x * y % mod;
};
segment_tree<int> st(N_MAX , 0 , stf);
segment_tree<LL> sf(N_MAX , 1 , sff);
int calc(){
   if(S.empty()){
      return st.range_query(1 , n);
   }
   LL val = 1;
   auto it = --S.end();
   vector<int> v;
   while(it != S.end()){
      val *= x[*it];
      if(val > 1E9){
         break;
      }
      v.emplace_back(*it);
      if(it == S.begin()){
         break;
      }
      --it;
   }
   int sz = (int)v.size();
   reverse(v.begin() , v.end());
   vector<int> vY(sz);
   for(int i = 0;i < sz;i ++){
      vY[i] = st.range_query(v[i] + 1 , (i == sz - 1 ? n : v[i + 1]));
   }
   //find suffix maximums
   vector<bool> g(sz);
   vector<int> t(sz);
   t[0] = x[v[0]];
   for(int i = 1;i < sz;i ++){
      t[i] = t[i - 1] * x[v[i]];
   }
   LL mx = 0;
   for(int i = sz - 1;i >= 0;i --){
      if(t[i] * vY[i] > mx){
         mx = t[i] * vY[i];
         g[i] = true;
      }
   }
   //best ending
   LL best = 0 , F = -1 , sum = 0 , prd = 1;
   for(int i = 0;i < sz;i ++){
      prd *= x[v[i]];
      if(g[i]){
         if(F != -1){
            sum += (prd - 1) * vY[i];
         }
         if(F == -1){
            LL P = sf.range_query(1 , v[i] + 1);
            --P;
            if(P < 0){
               P += mod;
            }
            F = P * vY[i] % mod;
         }
         prd = 1;
         best = max(best , sum + vY[i]);
      }
   }
   return (F + best) % mod;
}

int init(int N, int X[], int Y[]) {
   n = N;
   for(int i = 0;i < N;i ++){
      x[i] = X[i];
      if(X[i] > 1){
         S.insert(i);
      }
      sf.point_assign(i + 1 , X[i]);
      st.point_assign(i + 1 , Y[i]);
   }
   return calc();
}

int updateX(int pos, int val) {	
   if(x[pos] > 1){
      S.erase(pos);
   }
   x[pos] = val;
   if(x[pos] > 1){
      S.insert(pos);
   }
   sf.point_assign(pos + 1, x[pos]);
	return calc();
}

int updateY(int pos, int val) {
   st.point_assign(pos + 1 , val);
	return calc();
}

• Subtask 1: 17 / 17
• Subtask 2: 0 / 17
• Subtask 3: 0 / 20
• Subtask 4: 0 / 23
• Subtask 5: 0 / 23