oj.uz

Submission #678287

# Submission time Handle Problem Language Result Execution time Memory
678287 2023-01-05T11:53:31 Z arnold518 Seesaw (JOI22_seesaw) C++17
100 / 100
 149 ms 9612 KB 
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 2e5;

int N, A[MAXN+10];
ll S[MAXN+10];

bool cmp(pii p, pii q)
{
	p.first--; q.first--;
	return (__int128)(S[p.second]-S[p.first])*(q.second-q.first) < (__int128)(S[q.second]-S[q.first])*(p.second-p.first);
}

pii mmin(pii p, pii q)
{
	if(cmp(p, q)) return p;
	else return q;
}

pii mmax(pii p, pii q)
{
	if(cmp(p, q)) return q;
	return p;
}

pii B[MAXN+10], C[MAXN+10];
int T[MAXN+10];

double ans=1e18;

double avg(pii x)
{
	x.first--;
	return (double)(S[x.second]-S[x.first])/(x.second-x.first);
}

void f(pii l, pii r)
{
	//printf("%d %d / %d %d\n", l.first, l.second, r.first, r.second);
	ans=min(ans, avg(r)-avg(l));
}

struct CMP
{
	bool operator () (const pair<pii, int> &p, const pair<pii, int> &q) const
	{
		return !cmp(p.first, q.first);
	}
};

int main()
{
	scanf("%d", &N);
	for(int i=1; i<=N; i++) scanf("%d", &A[i]), S[i]=S[i-1]+A[i];

	for(int i=1; i<=N; i++)
	{
		int lo=0, hi=N-i+2;
		while(lo+1<hi)
		{
			int mid=lo+hi>>1;
			if(cmp(pii(mid, mid+i-1), pii(1, N))) lo=mid;
			else hi=mid;
		}
		B[i]=pii(lo, lo+i-1);
		C[i]=pii(hi, hi+i-1);
	}

	pii l(1, N), r(1, N);

	priority_queue<pair<pii, int>, vector<pair<pii, int>>, CMP> PQ;
	for(int i=1; i<=N; i++)
	{
		if(1<=B[i].first && C[i].second<=N) PQ.push({B[i], i}), r=mmax(r, B[i]);
		else if(1<=B[i].first) l=mmin(l, B[i]), r=mmax(r, B[i]);
		else l=mmin(l, C[i]), r=mmax(r, C[i]);
	}

	while(!PQ.empty())
	{
		auto t=PQ.top(); PQ.pop();
		f(mmin(l, t.first), r);
		//printf("WOW %d %d\n", t.first.first, t.first.second);
		r=mmax(r, C[t.second]);
		l=mmin(l, C[t.second]);
	}
	f(l, r);

	printf("%.10lf\n", ans);
}

Compilation message

seesaw.cpp: In function 'int main()':
seesaw.cpp:66:14: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   66 |    int mid=lo+hi>>1;
      |            ~~^~~
seesaw.cpp:58:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   58 |  scanf("%d", &N);
      |  ~~~~~^~~~~~~~~~
seesaw.cpp:59:31: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |  for(int i=1; i<=N; i++) scanf("%d", &A[i]), S[i]=S[i-1]+A[i];
      |                          ~~~~~^~~~~~~~~~~~~

Subtask #1
1.0 / 1.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct

Subtask #2
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 312 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct

Subtask #3
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 312 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 2 ms 456 KB Output is correct
10 Correct 2 ms 444 KB Output is correct
11 Correct 2 ms 456 KB Output is correct

Subtask #4
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 1 ms 312 KB Output is correct
5 Correct 1 ms 340 KB Output is correct
6 Correct 0 ms 340 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 340 KB Output is correct
9 Correct 2 ms 456 KB Output is correct
10 Correct 2 ms 444 KB Output is correct
11 Correct 2 ms 456 KB Output is correct
12 Correct 149 ms 9588 KB Output is correct
13 Correct 131 ms 9504 KB Output is correct
14 Correct 127 ms 9612 KB Output is correct
15 Correct 120 ms 9588 KB Output is correct
16 Correct 125 ms 9596 KB Output is correct