Submission #285564

#	Time	Username	Problem	Language	Result	Execution time	Memory
285564		TadijaSebez	Sparklers (JOI17_sparklers)	C++11	100 / 100	76 ms	4508 KiB

sparklers

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
const int N=100050;
bool check(vector<ll> a,vector<ll> b){
	if(a[0]<b[0])return 0;
	ll mx=a[0],mn=b[0];
	int i=1,j=1;
	while(1){
		if(i<a.size()&&a[i]>=mn)mx=max(mx,a[i++]);
		else if(j<b.size()&&b[j]<=mx)mn=min(mn,b[j++]);
		else break;
	}
	return i==a.size()&&j==b.size();
}
ll x[N],t;
int n,k;
bool check(ll s){
	vector<ll> a,b;
	for(int i=k;i>=1;i--)a.pb(x[i]-2*s*t*i);
	for(int i=k;i<=n;i++)b.pb(x[i]-2*s*t*i);
	if(!check(a,b))return 0;
	reverse(a.begin(),a.end());
	reverse(b.begin(),b.end());
	return check(a,b);
}
int main(){
	scanf("%i %i %lld",&n,&k,&t);
	for(int i=1;i<=n;i++)scanf("%lld",&x[i]);
	ll bot=0,top=1e9,mid,ans;
	while(top>=bot){
		mid=top+bot>>1;
		if(check(mid))ans=mid,top=mid-1;
		else bot=mid+1;
	}
	printf("%lld\n",ans);
	return 0;
}

Compilation message (stderr)

sparklers.cpp: In function 'bool check(std::vector<long long int>, std::vector<long long int>)':
sparklers.cpp:11:7: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |   if(i<a.size()&&a[i]>=mn)mx=max(mx,a[i++]);
      |      ~^~~~~~~~~
sparklers.cpp:12:12: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |   else if(j<b.size()&&b[j]<=mx)mn=min(mn,b[j++]);
      |           ~^~~~~~~~~
sparklers.cpp:15:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |  return i==a.size()&&j==b.size();
      |         ~^~~~~~~~~~
sparklers.cpp:15:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   15 |  return i==a.size()&&j==b.size();
      |                      ~^~~~~~~~~~
sparklers.cpp: In function 'int main()':
sparklers.cpp:33:10: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   33 |   mid=top+bot>>1;
      |       ~~~^~~~
sparklers.cpp:29:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   29 |  scanf("%i %i %lld",&n,&k,&t);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~
sparklers.cpp:30:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   30 |  for(int i=1;i<=n;i++)scanf("%lld",&x[i]);
      |                       ~~~~~^~~~~~~~~~~~~~

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