oj.uz

Submission #107508

# Submission time Handle Problem Language Result Execution time Memory
107508 2019-04-24T23:36:24 Z luciocf Building Bridges (CEOI17_building) C++14
100 / 100
 126 ms 11300 KB 
#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e5+10;

typedef long long ll;

typedef double dd;

struct Line
{
	char type;

	dd left;

	ll m, b;
};

typedef set<Line>::iterator sli;

ll h[maxn], w[maxn];
ll dp[maxn];

set<Line> env;

bool operator< (const Line &a, const Line &b)
{
	if (a.type+b.type > 0) return a.left < b.left;

	return a.m > b.m;
}

bool first(sli it)
{
	return (it == env.begin());
}

bool last(sli it)
{
	return (next(it) == env.end());
}

bool bad(Line l1, Line l2, Line l3)
{
	return (l3.b-l1.b)*(l1.m-l2.m) < (l1.m-l3.m)*(l2.b-l1.b);
}

dd intersect(Line l1, Line l2)
{
	return (dd)(l2.b-l1.b)/(l1.m-l2.m);
}

void get_left(sli it)
{
	if (!first(it))
	{
		Line l = *it;

		l.left = intersect(*prev(it), *it);

		env.erase(it); env.insert(l);
	}
}

void add(ll m, ll b)
{
	Line l = {0, 0, m, b};

	sli it = env.lower_bound(l);

	if (it != env.end() && it->m == l.m)
	{
		if (it->b <= l.b) return;
		env.erase(it);
	}

	env.insert(l);
	it = env.find(l);

	if (!first(it) && !last(it) && bad(*prev(it), *it, *next(it)))
	{
		env.erase(it);
		return;
	}

	while (!last(it) && !last(next(it)) && bad(*it, *next(it), *next(next(it))))
		env.erase(next(it));

	while (!first(it) && !first(prev(it)) && bad(*prev(prev(it)), *prev(it), *it))
		env.erase(prev(it));

	get_left(it);
	if (!last(it)) get_left(next(it));
}

ll query(ll x)
{
	sli it = env.upper_bound({1, (dd)x, 0, 0});
	it--;

	return (it->m * x + it->b);
}

int main(void)
{
	int n;
	scanf("%d", &n);

	for (int i = 1; i <= n; i++)
		scanf("%lld", &h[i]);

	ll S = 0;
	for (int i = 1; i <= n; i++)
		scanf("%lld", &w[i]), S += 1ll*w[i];

	dp[1] = -w[1];

	add(-2*h[1], h[1]*h[1]-w[1]);

	for (int i = 2; i <= n; i++)
	{
		ll val = query(h[i]);

		dp[i] = h[i]*h[i] - w[i] + val;

		add(-2*h[i], h[i]*h[i]+dp[i]);
	}

	printf("%lld\n", S+dp[n]);
}

Compilation message

building.cpp: In function 'int main()':
building.cpp:108:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
building.cpp:111:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld", &h[i]);
   ~~~~~^~~~~~~~~~~~~~~
building.cpp:115:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld", &w[i]), S += 1ll*w[i];
   ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 384 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 2 ms 384 KB Output is correct
5 Correct 3 ms 384 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 108 ms 3804 KB Output is correct
2 Correct 120 ms 3708 KB Output is correct
3 Correct 126 ms 3924 KB Output is correct
4 Correct 115 ms 3576 KB Output is correct
5 Correct 87 ms 5112 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 384 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 2 ms 384 KB Output is correct
5 Correct 3 ms 384 KB Output is correct
6 Correct 108 ms 3804 KB Output is correct
7 Correct 120 ms 3708 KB Output is correct
8 Correct 126 ms 3924 KB Output is correct
9 Correct 115 ms 3576 KB Output is correct
10 Correct 87 ms 5112 KB Output is correct
11 Correct 98 ms 3900 KB Output is correct
12 Correct 120 ms 3700 KB Output is correct
13 Correct 62 ms 3700 KB Output is correct
14 Correct 101 ms 3860 KB Output is correct
15 Correct 120 ms 11300 KB Output is correct
16 Correct 98 ms 5116 KB Output is correct
17 Correct 23 ms 3704 KB Output is correct
18 Correct 24 ms 3704 KB Output is correct