oj.uz

Submission #107509

# Submission time Handle Problem Language Result Execution time Memory
107509 2019-04-24T23:47:10 Z luciocf Building Bridges (CEOI17_building) C++14
100 / 100
 131 ms 10464 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 x;

	ll m, b;
};

typedef set<Line>::iterator sit;

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.x < b.x;

	return a.m > b.m;
}

bool hasPrev(sit it)
{
	return (it != env.begin());
}

bool hasNext(sit it)
{
	return (next(it) != env.end());
}

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

bool bad(Line l1, Line l2, Line l3)
{
	return intersect(l1, l3) < intersect(l1, l2);
}

void get_x(sit it)
{
	if (hasPrev(it))
	{
		Line l = *it;

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

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

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

	sit 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 (hasPrev(it) && hasNext(it) && bad(*prev(it), *it, *next(it)))
	{
		env.erase(it);
		return;
	}

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

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

	get_x(it);
	if (hasNext(it)) get_x(next(it));
}

ll query(ll x)
{
	sit 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 3 ms 256 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 3 ms 384 KB Output is correct
5 Correct 2 ms 384 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 98 ms 2808 KB Output is correct
2 Correct 110 ms 2808 KB Output is correct
3 Correct 98 ms 2808 KB Output is correct
4 Correct 97 ms 2652 KB Output is correct
5 Correct 87 ms 4344 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 256 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 2 ms 384 KB Output is correct
4 Correct 3 ms 384 KB Output is correct
5 Correct 2 ms 384 KB Output is correct
6 Correct 98 ms 2808 KB Output is correct
7 Correct 110 ms 2808 KB Output is correct
8 Correct 98 ms 2808 KB Output is correct
9 Correct 97 ms 2652 KB Output is correct
10 Correct 87 ms 4344 KB Output is correct
11 Correct 106 ms 2684 KB Output is correct
12 Correct 131 ms 2808 KB Output is correct
13 Correct 72 ms 2720 KB Output is correct
14 Correct 109 ms 2680 KB Output is correct
15 Correct 119 ms 10464 KB Output is correct
16 Correct 88 ms 4184 KB Output is correct
17 Correct 23 ms 2680 KB Output is correct
18 Correct 21 ms 2680 KB Output is correct