Submission #864570

#	Time	Username	Problem	Language	Result	Execution time	Memory
864570		manizare	Sparklers (JOI17_sparklers)	C++14	0 / 100	1 ms	4564 KiB

sparklers

#include <bits/stdc++.h> 
 
#pragma GCC optimize("O3,unroll-loops")
#define pb push_back
#define F first
#define S second 
#define all(a) a.begin(),a.end()
#define pii pair <int,int>
#define Pii pair< pii , pii >
#define int long long
#define ld long double 
using namespace std ;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxn = 6e5 + 10 , sq = 3 , maxq = 1e7 + 1 ,  inf = 1e18 + 10 , mod= 998244353 ,lg = 20 ;
int n ,t , k;
vector <ld> a , b ;
int x[maxn] ; 
ld pa[maxn] , pb[maxn] , ma[maxn] , mb[maxn] ; 
int sl(){
  vector <int> va , vb ; 
  va.pb(0);vb.pb(0);
  for(int i = 1; i < a.size() ; i++){
    pa[i] = pa[i-1] + a[i] ;
    if(pa[i] > pa[va.back()]){
      ma[va.size()-1] = 0 ;
      for(int j = va.back() + 1 ; j < i ; j++){
        ma[va.size()-1] = min(ma[va.size()-1] , pa[j] - pa[va.back()]) ;
      }
      va.pb(i) ;
    }
  }
  for(int i = 1; i < b.size() ; i++){
    pb[i] = pb[i-1] + b[i] ;
    if(pb[i] > pb[vb.back()]){
      mb[vb.size()-1] = 0 ;
      for(int j = vb.back() + 1 ; j < i ; j++){
        mb[vb.size()-1] = min(mb[vb.size()-1] , pb[j] - pb[vb.back()]) ;
      }
      vb.pb(i) ;
    }
  }
  int id1 = 0 , id2 =0 , val = 0 ;
  while(1){
    if(id1!=va.size()-1 && pa[va[id1]]+pb[vb[id2]]+ma[id1] >=0 ){
      id1++;
      continue ;
    }
    if(id2!=vb.size()-1 && pa[va[id1]]+pb[vb[id2]]+mb[id2] >= 0){
      id2++;
      continue ;
    }
    break ;
  }
  if(id1!=va.size()-1 || id2 != vb.size()-1){
    return 0 ;
  }
  id1 = va[id1] + 1 ;
  id2 = vb[id2] + 1 ;
  vector<ld> vec , vec2 ;
  for(int i =id1 ; i < a.size() ; i++)vec.pb(a[i]) ;
  for(int i =id2 ; i < b.size() ; i++)vec.pb(b[i]) ;
  for(int i =id2 ; i < b.size() ; i++)vec2.pb(b[i]) ;
  for(int i =id1 ; i < a.size() ; i++)vec2.pb(a[i]) ;
  ld sm = pa[id1-1] + pb[id2-1] ;
  bool ok1 =1 ,ok2 =1 ;
  for(int i =0 ; i < vec.size() ;i++){
    sm += vec[i] ;
    if(sm < 0)ok1 =0 ; 
  }
  sm =pa[id1-1] +pb[id2-1] ;
  for(int i=  0 ; i < vec2.size() ; i++){
    sm+=vec2[i] ;
    if(sm < 0)ok2 =0 ;
  }
  return ok1|ok2 ;
}

bool ch(int z){
  a.clear();b.clear();
  a.pb(0);
  b.pb(0) ;
  a.pb((ld)t); 
  for(int i = k+1; i <= n ; i++){
    a.pb(-(ld)(x[i] - x[i-1])/(ld)(2*(ld)z));
    a.pb((ld)t) ;
  }
  for(int i = k-1 ; i >= 1; i--){
    b.pb(-(ld)(x[i+1] - x[i])/(ld)(2*(ld)z));
    b.pb((ld)t) ;
  }
  return sl() ;
}

signed main() {
  ios::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0) ;

  cin >> n >> k >> t ;
  for(int i = 1; i <= n ; i++){
    cin >> x[i] ;
  }
  int l = 0 , r = 1e9 ; 
  while(r-l>1){
    int mid = (l+r)/2 ;
    if(ch(mid) == 1)r= mid ;
    else l = mid ;
  }
  cout << r << "\n";
}
/*
 
*/

Compilation message (stderr)

sparklers.cpp: In function 'long long int sl()':
sparklers.cpp:22:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |   for(int i = 1; i < a.size() ; i++){
      |                  ~~^~~~~~~~~~
sparklers.cpp:32:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |   for(int i = 1; i < b.size() ; i++){
      |                  ~~^~~~~~~~~~
sparklers.cpp:44:11: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |     if(id1!=va.size()-1 && pa[va[id1]]+pb[vb[id2]]+ma[id1] >=0 ){
      |        ~~~^~~~~~~~~~~~~
sparklers.cpp:48:11: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   48 |     if(id2!=vb.size()-1 && pa[va[id1]]+pb[vb[id2]]+mb[id2] >= 0){
      |        ~~~^~~~~~~~~~~~~
sparklers.cpp:54:9: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |   if(id1!=va.size()-1 || id2 != vb.size()-1){
      |      ~~~^~~~~~~~~~~~~
sparklers.cpp:54:30: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |   if(id1!=va.size()-1 || id2 != vb.size()-1){
      |                          ~~~~^~~~~~~~~~~~~~
sparklers.cpp:60:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |   for(int i =id1 ; i < a.size() ; i++)vec.pb(a[i]) ;
      |                    ~~^~~~~~~~~~
sparklers.cpp:61:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |   for(int i =id2 ; i < b.size() ; i++)vec.pb(b[i]) ;
      |                    ~~^~~~~~~~~~
sparklers.cpp:62:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   62 |   for(int i =id2 ; i < b.size() ; i++)vec2.pb(b[i]) ;
      |                    ~~^~~~~~~~~~
sparklers.cpp:63:22: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |   for(int i =id1 ; i < a.size() ; i++)vec2.pb(a[i]) ;
      |                    ~~^~~~~~~~~~
sparklers.cpp:66:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |   for(int i =0 ; i < vec.size() ;i++){
      |                  ~~^~~~~~~~~~~~
sparklers.cpp:71:21: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |   for(int i=  0 ; i < vec2.size() ; i++){
      |                   ~~^~~~~~~~~~~~~
sparklers.cpp:42:26: warning: unused variable 'val' [-Wunused-variable]
   42 |   int id1 = 0 , id2 =0 , val = 0 ;
      |                          ^~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 20
• Subtask 3: 0 / 50