Submission #1063610

#	Time	Username	Problem	Language	Result	Execution time	Memory
1063610		TimDee	Seesaw (JOI22_seesaw)	C++17	0 / 100	64 ms	348 KiB

seesaw

#include <bits/stdc++.h>
using namespace std;

#define forn(i,n) for(int i=0; i<n; ++i)
#define vii(a,n) vector<int> a(n); forn(i,n) cin>>a[i];
#define f first
#define s second
#define pb push_back
#define all(x) x.begin(),x.end()

#define double long double
const double one = 1;
const int N=1005;
double med[N][N];

int a[N];

double bad(int n) {

	vector<pair<double,int>> v;
	forn(i,n) {
		int s=0;
		for(int j=i; j<n; ++j) {
			s+=a[j];
			double z = 1.0*s/(j-i+1);
			v.pb({z,j-i});
		}
	}
	sort(all(v));
	vector<int> cnt(n);
	int tot=0;
	int r=0;
	double ans=a[n-1]-a[0];
	forn(i,v.size()) {
		while (r<v.size() && tot<n) {
			tot+=!cnt[v[r].s];
			++cnt[v[r].s];
			++r;
		}
		if (tot==n) ans=min(ans,v[r-1].f - v[i].f);
		--cnt[v[i].s];
		tot-=!cnt[v[i].s];
	}
	return ans;
	cout<<fixed<<setprecision(10)<<ans<<'\n';

}

double good(int n) {

	int sum=0; forn(i,n) sum+=a[i];
	double ans = a[n-1]-a[0];
	const double z = one*sum/n;
	forn(mask,1<<(n-1)) {
		int l=0, r=n-1;
		double lx=z, rx=z;
		int s=sum;
		forn(i,n-1) {
			if ((mask>>i)&1) {
				s-=a[l++];
			} else {
				s-=a[r--];
			}
			lx = min(lx,one*s/(r-l+1));
			rx = max(rx,one*s/(r-l+1));
		}
		//cout<<"??? "<<mask<<"  "<<lx<<' '<<rx<<'\n';
		ans=min(ans,rx-lx);
	}
	return ans;

}

void solve() {
	
	int n; cin>>n;
	forn(i,n) cin>>a[i];
	cout<<fixed<<setprecision(9)<<good(n)<<'\n';

}

mt19937 rng(1337);

int rand(int a, int b) {
	return a + rng()%(b-a+1);
}
void gen() {
	int n=rand(2,6);
	a[0]=rand(1,10);
	for(int i=1; i<n; ++i) a[i]=rand(a[i-1]+1,10+i);
	auto f = good(n);
	auto s = bad(n);
	const double eps = 1e-9;
	if (abs(f-s)>eps) {
		cout<<"WA\n";
		cout<<n<<'\n';
		forn(i,n) cout<<a[i]<<' '; cout<<'\n';
		cout<<fixed<<setprecision(10)<<"AC: "<<f<<" , WA: "<<s<<'\n';
		exit(0);
	}
}

int32_t main() {
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	//while (1) gen();
	solve();
}

Compilation message (stderr)

seesaw.cpp: In function 'long double bad(int)':
seesaw.cpp:4:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long double, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    4 | #define forn(i,n) for(int i=0; i<n; ++i)
......
   34 |  forn(i,v.size()) {
      |       ~~~~~~~~~~                 
seesaw.cpp:34:2: note: in expansion of macro 'forn'
   34 |  forn(i,v.size()) {
      |  ^~~~
seesaw.cpp:35:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long double, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   35 |   while (r<v.size() && tot<n) {
      |          ~^~~~~~~~~
seesaw.cpp: In function 'void gen()':
seesaw.cpp:4:19: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
    4 | #define forn(i,n) for(int i=0; i<n; ++i)
      |                   ^~~
seesaw.cpp:97:3: note: in expansion of macro 'forn'
   97 |   forn(i,n) cout<<a[i]<<' '; cout<<'\n';
      |   ^~~~
seesaw.cpp:97:30: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   97 |   forn(i,n) cout<<a[i]<<' '; cout<<'\n';
      |                              ^~~~

• Subtask 1: 0 / 1
• Subtask 2: 0 / 33
• Subtask 3: 0 / 33
• Subtask 4: 0 / 33