Submission #63156

#	Time	Username	Problem	Language	Result	Execution time	Memory
63156		khsoo01	Building Bridges (CEOI17_building)	C++11	100 / 100	206 ms	17336 KiB

building

#include<bits/stdc++.h>
#define X first
#define Y second
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
const ll N = 100005, L = 18, inf = 1e18;

ll n, def, h[N], a[N], d[N];

ll val (pll &P, ll V) {return P.X*V+P.Y;}

bool valid (pll &A, pll &B, pll &C) {
	return (B.Y-A.Y) * (B.X-C.X)  < (C.Y-B.Y) * (A.X-B.X);
}

struct hull {
	vector<pll> v;
	void upd (pll P) {
		for(ll i=v.size();i--;) {
			if(v[i].X != P.X) break;
			else v.pop_back();
		}
		for(ll i=v.size();i-->1;) {
			if(valid(v[i-1], v[i], P)) break;
			else v.pop_back();
		}
		v.push_back(P);
	}
	ll get (ll P) {
		if(v.empty()) return inf;
		ll S = 0, E = (int)v.size()-1;
		while(S<E) {
			ll M = (S+E)/2;
			val(v[M], P) < val(v[M+1], P) ? E = M : S = M+1;
		}
		return val(v[S], P);
	}
} x[L];

void Merge (hull &A, hull &B) {
	vector<pll> V;
	for(int i=0,j=0;i<A.v.size()||j<B.v.size();) {
		bool flag = false;
		if(i == A.v.size()) flag = true;
		else if(j == B.v.size()) flag = false;
		else if(A.v[i] < B.v[j]) flag = true;
		if(flag) {V.push_back(B.v[j]); j++;}
		else {V.push_back(A.v[i]); i++;}
	}
	A.v.clear(); B.v.clear();
	for(auto &T : V) A.upd(T);
}

int main()
{
	scanf("%lld",&n);
	for(ll i=1;i<=n;i++) scanf("%lld",&h[i]);
	for(ll i=1;i<=n;i++) {scanf("%lld",&a[i]); def += a[i];}
	x[0].upd(pll(-2*h[1], h[1]*h[1]-a[1]));
	for(ll i=2;i<=n;i++) {
		d[i] = inf;
		for(ll j=0;j<L;j++) {
			d[i] = min(d[i], x[j].get(h[i])-a[i]+h[i]*h[i]);
		}
		hull tmp;
		tmp.upd(pll(-2*h[i], h[i]*h[i]+d[i]));
		for(ll j=0;j<L;j++) {
			if(x[j].v.empty()) {swap(x[j], tmp); break;}
			else Merge(tmp, x[j]);
		}
	}
	printf("%lld\n",d[n]+def);
}

Compilation message (stderr)

building.cpp: In function 'void Merge(hull&, hull&)':
building.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0,j=0;i<A.v.size()||j<B.v.size();) {
                  ~^~~~~~~~~~~
building.cpp:43:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0,j=0;i<A.v.size()||j<B.v.size();) {
                                ~^~~~~~~~~~~
building.cpp:45:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(i == A.v.size()) flag = true;
      ~~^~~~~~~~~~~~~
building.cpp:46:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   else if(j == B.v.size()) flag = false;
           ~~^~~~~~~~~~~~~
building.cpp: In function 'int main()':
building.cpp:57:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld",&n);
  ~~~~~^~~~~~~~~~~
building.cpp:58:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(ll i=1;i<=n;i++) scanf("%lld",&h[i]);
                       ~~~~~^~~~~~~~~~~~~~
building.cpp:59:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(ll i=1;i<=n;i++) {scanf("%lld",&a[i]); def += a[i];}
                        ~~~~~^~~~~~~~~~~~~~

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