Submission #113896

#	Time	Username	Problem	Language	Result	Execution time	Memory
113896		Mahdi_Jfri	Building Bridges (CEOI17_building)	C++14	100 / 100	68 ms	9028 KiB

building

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back

bool Q;
struct Line {
	mutable ll k, m, p;
	bool operator<(const Line& o) const {
		return Q ? p < o.p : k < o.k;
	}
};

struct LineContainer : multiset<Line> {
	// (for doubles, use inf = 1/.0, div(a,b) = a/b)
	const ll inf = LLONG_MAX;
	ll div(ll a, ll b) { // floored division
		return a / b - ((a ^ b) < 0 && a % b); }
	bool isect(iterator x, iterator y) {
		if (y == end()) { x->p = inf; return false; }
		if (x->k == y->k) x->p = x->m > y->m ? inf : -inf;
		else x->p = div(y->m - x->m, x->k - y->k);
		return x->p >= y->p;
	}
	void add(ll k, ll m) {
		auto z = insert({k, m, 0}), y = z++, x = y;
		while (isect(y, z)) z = erase(z);
		if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
		while ((y = x) != begin() && (--x)->p >= y->p)
			isect(x, erase(y));
	}
	ll query(ll x) {
		assert(!empty());
		Q = 1; auto l = *lower_bound({0,0,x}); Q = 0;
		return l.k * x + l.m;
	}
};

LineContainer cht;

const int maxn = 1e5 + 20;

ll dp[maxn];

int h[maxn] , w[maxn];

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int n;
	cin >> n;

	for(int i = 0; i < n; i++)
		cin >> h[i];

	ll sum = 0;
	for(int i = 0; i < n; i++)
		cin >> w[i] , sum += w[i];

	for(int i = 0; i < n; i++)
	{
		if(!i)
			dp[0] = -w[0];
		else
			dp[i] = 1LL * h[i] * h[i] - cht.query(h[i]) - w[i];

		cht.add(2 * h[i] , -dp[i] - 1LL * h[i] * h[i]);
	}

	cout << dp[n - 1] + sum << endl;
}

• Subtask 1: 30 / 30
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40