Submission #498526

#	Time	Username	Problem	Language	Result	Execution time	Memory
498526		codebuster_10	Walk (CEOI06_walk)	C++17	72 / 100	223 ms	31660 KiB

walk

#include <bits/stdc++.h>
using namespace std;

#define int int64_t //be careful about this 

#define pr pair
#define ar array
#define f first
#define s second
#define vt vector
#define pb push_back
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound

#define SZ(x) ((int)(x).size())
#define all(a) (a).begin(),(a).end()
#define allr(a) (a).rbegin(),(a).rend()
#define mem(a,b) memset(a, b, sizeof(a))

template<class A> void rd(vt<A>& v);
template<class T> void rd(T& x){ cin >> x;}
template<class H, class... T> void rd(H& h, T&... t) { rd(h); rd(t...);}
template<class A> void rd(vt<A>& x) { for(auto& a : x) rd(a);}

template<class T> bool ckmin(T& a, const T b) { return b < a ? a = b, 1 : 0;}
template<class T> bool ckmax(T& a, const T b) { return a < b ? a = b, 1 : 0;}

template<typename T>
void __p(T a) {
	cout<<a; 
}
template<typename T, typename F>
void __p(pair<T, F> a) {
	cout<<"{";
	__p(a.first);
	cout<<",";
	__p(a.second);
	cout<<"}\n"; 
}
template<typename T>
void __p(std::vector<T> a) {
	cout<<"{";
	for(auto it=a.begin(); it<a.end(); it++)
		__p(*it),cout<<",}\n"[it+1==a.end()]; 
}
template<typename T, typename ...Arg>
void __p(T a1, Arg ...a) {
	__p(a1);
	__p(a...);
}
template<typename Arg1>
void __f(const char *name, Arg1 &&arg1) {
	cout<<name<<" : ";
	__p(arg1);
	cout<<endl;
}
template<typename Arg1, typename ... Args>
void __f(const char *names, Arg1 &&arg1, Args &&... args) {
	int bracket=0,i=0;
	for(;; i++)
		if(names[i]==','&&bracket==0)
			break;
		else if(names[i]=='(')
			bracket++;
		else if(names[i]==')')
			bracket--;
	const char *comma=names+i;
	cout.write(names,comma-names)<<" : ";
	__p(arg1);
	cout<<" | ";
	__f(comma+1,args...);
}
#define trace(...) cout<<"Line:"<<__LINE__<<"  ", __f(#__VA_ARGS__, __VA_ARGS__)


void setIO(string s = "") {
	ios_base::sync_with_stdio(0); cin.tie(0); 
	cout.precision(20); cout << fixed;
	if(SZ(s)){
		freopen((s+".in").c_str(),"r",stdin);
		freopen((s+".out").c_str(),"w",stdout);
	}
}


/*/--------------------------------------------------look below-----------------------------------------------------------------------------------/*/

















const int inf = 1e9;





struct R{
	int X1,Y1,X2,Y2,id;
};

signed main(){
	setIO();

	int FX,FY;
	rd(FX,FY);

	int n;
	rd(n);
	vt<R> rect(n);
	for(int i = 0; i < n; ++i)
		rect[i].id=i,rd(rect[i].X1,rect[i].Y1,rect[i].X2,rect[i].Y2);
	rect.pb({FX,FY,FX,FY,n});

	vt<int> nxtu(n+1,-1),nxtl(n+1,-1);

	vt<ar<int,3>> events;

	for(int i = 0; i <= n; ++i){
		events.pb({rect[i].Y1-1,+1,rect[i].id});
		events.pb({rect[i].Y2+1,-1,rect[i].id});
		events.pb({rect[i].Y1,+2,rect[i].id});//activate
		events.pb({rect[i].Y2,-2,rect[i].id});//deactivate.
	}

	sort(all(events),[&](auto l,auto r){
		if(l[0] != r[0])
			return l[0] < r[0];
		return l[1] > r[1];
	});

	auto cmp = [&](int i,int j){
		return rect[i].X2 < rect[j].X2;
	};
	set<int,decltype(cmp)> s(cmp);

	for(auto [y,t,id] : events){
		if(t == -1 || t == +1){
			if(s.empty())
				continue;
			auto itr = s.lb(id);
			if(itr != s.begin())
				--itr;
			else
				continue;
			if(t == -1)
				nxtu[id] = *itr;
			else
				nxtl[id] = *itr;
		}
		if(t == +2){
			s.insert(id);
		}
		if(t == -2){
			s.erase(s.find(id));
		}
	}

	vt<int> id(n+1);
	iota(all(id),0);

	sort(all(id),[&](auto l,auto r){
		return rect[l].X2 < rect[r].X2;
	});

	int ans = inf;

	vt<int> disu(n+1,inf),disl(n+1,inf);

	map<pr<int,int>,pr<int,int>> par;

	for(auto i : id){
		if(rect[i].id == n){
			if(nxtu[rect[i].id] < 0)
				ckmin(ans,abs(rect[i].X2) + abs(rect[i].Y2)),par[{FX,FY}] = {0,0};
			else{
				int nxt = nxtu[rect[i].id];
				if(ckmin(ans,disu[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2-(rect[nxt].Y2+1))))
					par[{FX,FY}] = {rect[nxt].X2,rect[nxt].Y2+1};
				if(ckmin(ans,disl[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2-(rect[nxt].Y1-1))))
					par[{FX,FY}] = {rect[nxt].X2,rect[nxt].Y1-1};
			}
			if(nxtl[rect[i].id] < 0)
				ckmin(ans,abs(rect[i].X2) + abs(rect[i].Y2));
			else{
				int nxt = nxtl[rect[i].id];
				if(ckmin(ans,disu[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2-(rect[nxt].Y2+1))))
					par[{FX,FY}] = {rect[nxt].X2,rect[nxt].Y2+1};
				if(ckmin(ans,disl[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2-(rect[nxt].Y1-1))))
					par[{FX,FY}] = {rect[nxt].X2,rect[nxt].Y1-1};
			}
			vt<pr<int,int>> out;
			while(FX != 0 || FY != 0){
				auto p = par[{FX,FY}];
				out.eb(0,FY-p.s);
				out.eb(FX-p.f,0);
				FX=p.f,FY=p.s;
			}
			cout << ans << "\n";
			reverse(all(out));
			cout << SZ(out) << "\n";
			for(auto [x,y] : out)
				cout << x << " " << y << "\n";
			return 0;
		}

		if(nxtu[rect[i].id] < 0)
			disu[rect[i].id] = abs(rect[i].X2) + abs(rect[i].Y2+1), par[{rect[i].X2,rect[i].Y2+1}] = {0,0};
		else{
			int nxt = nxtu[rect[i].id];
			if(ckmin(disu[rect[i].id],disu[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2-rect[nxt].Y2)))
				par[{rect[i].X2,rect[i].Y2+1}] = {rect[nxt].X2,rect[nxt].Y2+1};
			if(ckmin(disu[rect[i].id],disl[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y2+1-(rect[nxt].Y1-1))))
				par[{rect[i].X2,rect[i].Y2+1}] = {rect[nxt].X2,rect[nxt].Y1-1};
		}
		if(nxtl[rect[i].id] < 0)
			disl[rect[i].id] = abs(rect[i].X2) + abs(rect[i].Y1-1), par[{rect[i].X2,rect[i].Y1-1}] = {0,0};
		else{
			int nxt = nxtl[rect[i].id];
			if(ckmin(disl[rect[i].id],disu[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y1-1-(rect[nxt].Y2+1))))
				par[{rect[i].X2,rect[i].Y1-1}] = {rect[nxt].X2,rect[nxt].Y2+1};
			if(ckmin(disl[rect[i].id],disl[nxt] + abs(rect[i].X2-rect[nxt].X2) + abs(rect[i].Y1-rect[nxt].Y1)))
				par[{rect[i].X2,rect[i].Y1-1}] = {rect[nxt].X2,rect[nxt].Y1-1};
		}
	}

	return 0;
}







// tips to avoid bugs.

/*
	* be careful of whats happening you dont want a continue statement to miss imp line of code.
	* be careful when to update what since it might be needed in next segment of code.
	* dont get stuck on one idea.
	* dont use too much space bar so that code is written quickly as possible.
*/

Compilation message (stderr)

walk.cpp: In function 'void setIO(std::string)':
walk.cpp:81:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |   freopen((s+".in").c_str(),"r",stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
walk.cpp:82:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |   freopen((s+".out").c_str(),"w",stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 72 / 100