Submission #956871

#	Time	Username	Problem	Language	Result	Execution time	Memory
956871		Trisanu_Das	Building Bridges (CEOI17_building)	C++17	0 / 100	51 ms	2396 KiB

building

#include <bits/stdc++.h>
using namespace std;
#define ll long long
 
struct Line {
	mutable ll k, m, p;
	bool operator<(const Line& o) const { return k < o.k; }
	bool operator<(ll x) const { return p < x; }
};
 
struct LineContainer : multiset<Line, less<>> {
	// (for doubles, use inf = 1/.0, div(a,b) = a/b)
	static 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()) return x->p = inf, 0;
		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());
		auto l = *lower_bound(x);
		return l.k * x + l.m;
	}
};
 
int main(){
  int n; cin >> n;
  int h[n + 2], w[n + 2], dp[n + 1];
  for(int i = 1; i <= n; i++) cin >> h[i];
  for(int i = 1; i <= n; i++) cin >> w[i];
  LineContainer hull;
  dp[1] = -w[1];
  for(int i = 2; i <= n; i++){
    hull.add(2 * h[i - 1], h[i - 1] * h[i - 1] + dp[i - 1]);
    dp[i] = hull.query(h[i]) + h[i] * h[i] - w[i];
  }
  cout << dp[n] + accumulate(w + 1, w + n + 1, 0) << '\n';
}

• Subtask 1: 0 / 30
• Subtask 2: 0 / 30
• Subtask 3: 0 / 40