Submission #333847

#	Time	Username	Problem	Language	Result	Execution time	Memory
333847		jc713	Demarcation (BOI14_demarcation)	C++17	100 / 100	173 ms	18316 KiB

demarcation

#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <bits/stdc++.h>

using namespace std;
using namespace __gnu_pbds;
template <class T> using Tree = tree<T, null_type, less<T>,
    rb_tree_tag, tree_order_statistics_node_update>;
 
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using db = double; 
using str = string; // yay python!

using pi = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;

using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>; 
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>; 
using vpd = vector<pd>;

#define tcT template<class T
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>; 
tcT, size_t SZ> using AR = array<T,SZ>; 

// pairs
#define mp make_pair
#define f first
#define s second

// vectors
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define sor(x) sort(all(x)) 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

// loops
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353
const int MX = 2e5+5;
const ll INF = 1e18; // not too close to LLONG_MAX
const int IINF = 1e9;
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 

// helper funcs
constexpr int pct(int x) { return __builtin_popcount(x); } // # of bits set
constexpr int bits(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
ll cdiv(ll a, ll b) { return a/b+((a^b)>0&&a%b); } // divide a by b rounded up
ll fdiv(ll a, ll b) { return a/b-((a^b)<0&&a%b); } // divide a by b rounded down

tcT> bool ckmin(T& a, const T& b) {
    return b < a ? a = b, 1 : 0; } // set a = min(a,b)
tcT> bool ckmax(T& a, const T& b) {
    return a < b ? a = b, 1 : 0; }

#define tcTU tcT, class U
tcTU> T fstTrue(T lo, T hi, U f) {
    hi ++; assert(lo <= hi); // assuming f is increasing
    while (lo < hi) { // find first index such that f is true 
        T mid = lo+(hi-lo)/2;
        f(mid) ? hi = mid : lo = mid+1; 
    } 
    return lo;
}
tcTU> T lstTrue(T lo, T hi, U f) {
    lo --; assert(lo <= hi); // assuming f is decreasing
    while (lo < hi) { // find first index such that f is true 
        T mid = lo+(hi-lo+1)/2;
        f(mid) ? lo = mid : hi = mid-1;
    } 
    return lo;
}
tcT> void remDup(vector<T>& v) { // sort and remove duplicates
    sort(all(v)); v.erase(unique(all(v)),end(v)); }
tcTU> void erase(T& t, const U& u) { // don't erase
    auto it = t.find(u); assert(it != end(t));
    t.erase(u); } // element that doesn't exist from (multi)set

// INPUT
#define tcTUU tcT, class ...U
tcT> void re(complex<T>& c);
tcTU> void re(pair<T,U>& p);
tcT> void re(vector<T>& v);
tcT, size_t SZ> void re(AR<T,SZ>& a);

tcT> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
tcTUU> void re(T& t, U&... u) { re(t); re(u...); }

tcT> void re(complex<T>& c) { T a,b; re(a,b); c = {a,b}; }
tcTU> void re(pair<T,U>& p) { re(p.f,p.s); }
tcT> void re(vector<T>& x) { trav(a,x) re(a); }
tcT, size_t SZ> void re(AR<T,SZ>& x) { trav(a,x) re(a); }

// TO_STRING
#define ts to_string
str ts(char c) { return str(1,c); }
str ts(const char* s) { return (str)s; }
str ts(str s) { return s; }
str ts(bool b) { 
    #ifdef LOCAL
        return b ? "true" : "false"; 
    #else 
        return ts((int)b);
    #endif
}
tcT> str ts(complex<T> c) { 
    stringstream ss; ss << c; return ss.str(); }
str ts(vector<bool> v) {
    str res = "{"; F0R(i,sz(v)) res += char('0'+v[i]);
    res += "}"; return res; }
template<size_t SZ> str ts(bitset<SZ> b) {
    str res = ""; F0R(i,SZ) res += char('0'+b[i]);
    return res; }
tcTU> str ts(pair<T,U> p);
tcT> str ts(T v) { // containers with begin(), end()
    #ifdef LOCAL
        bool fst = 1; str res = "{";
        for (const auto& x: v) {
            if (!fst) res += ", ";
            fst = 0; res += ts(x);
        }
        res += "}"; return res;
    #else
        bool fst = 1; str res = "";
        for (const auto& x: v) {
            if (!fst) res += " ";
            fst = 0; res += ts(x);
        }
        return res;

    #endif
}
tcTU> str ts(pair<T,U> p) {
    #ifdef LOCAL
        return "("+ts(p.f)+", "+ts(p.s)+")"; 
    #else
        return ts(p.f)+" "+ts(p.s);
    #endif
}

// OUTPUT
tcT> void pr(T x) { cout << ts(x); }
tcTUU> void pr(const T& t, const U&... u) { 
    pr(t); pr(u...); }
void ps() { pr("\n"); } // print w/ spaces
tcTUU> void ps(const T& t, const U&... u) { 
    pr(t); if (sizeof...(u)) pr(" "); ps(u...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
tcTUU> void DBG(const T& t, const U&... u) {
    cerr << ts(t); if (sizeof...(u)) cerr << ", ";
    DBG(u...); }
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
    #define dbg(...) cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
    #define chk(...) if (!(__VA_ARGS__)) cerr << "Line(" << __LINE__ << ") -> function(" \
         << __FUNCTION__  << ") -> CHK FAILED: (" << #__VA_ARGS__ << ")" << "\n", exit(0);
#else
    #define dbg(...) 0
    #define chk(...) 0
#endif

// FILE I/O
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIO(str s = "") {
    unsyncIO();
    // cin.exceptions(cin.failbit); 
    // throws exception when do smth illegal
    // ex. try to read letter into int
    if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}

struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

int N;
ll PERM = 0;

void shift(vpl& p){
	pl poi = mp(INF, INF);
	trav(a, p)
		ckmin(poi, a);
	trav(a, p)
		a = mp(a.f - poi.f, a.s - poi.s);
}

void rotate(vpl& p){
	vpl ret;
	trav(a, p)
		ret.pb(mp(a.s, -a.f));
	p = ret;
}

void reflect(vpl& p){
	vpl ret;
	trav(a, p)
		ret.pb(mp(a.f, -a.s));
	p = ret;
}

bool equiv(vpl& A, vpl& B){
	set<pl> con;
	trav(a, A)
		con.insert(a);
	trav(a, B)
		if(con.count(a) == 0)
			return false;
	return (sz(A) == sz(B));
}

bool check(vpl& A, vpl& B){
	shift(A);
	shift(B);
	F0R(i, 4){
		rotate(A);
		shift(A);
		if(equiv(A, B))
			return true;
	}
	reflect(A);
	F0R(i, 4){
		rotate(A);
		shift(A);
		if(equiv(A, B))
			return true;
	}
	return false;
}

set<pair<pl, pl>> s;
map<pair<pl, pl>, pi> ind;
bool flip;

bool solve(vpl p){
	ll dist = 0;
	int i = 0;
	s.clear();
	ind.clear();
	F0R(a, sz(p)){
		while(i < sz(p)){
			if(dist + abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f) >= PERM / 2)
				break;
			dist += abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f);
			i++;
		}
		if(i == sz(p))
			break;
		while(i < sz(p)){
			pair<pl, pl> x = mp(p[a], p[(a + 1) % N]);
			pair<pl, pl> y = mp(p[i], p[(i + 1) % N]);
			if(x.f.s == x.s.s && y.f.s == y.s.s){
				if((x.f.f > x.s.f) != (y.f.f > y.s.f)){
						if(y.f.f > y.s.f){
							ll init = y.f.f - (PERM / 2 - dist);
							if((init - x.f.f) % 2 == 0 && (init + x.f.f) / 2 >= x.f.f &&
									(init + x.f.f) / 2 <= y.f.f &&
									(init + x.f.f) / 2 <= x.s.f && (init + x.f.f) / 2 >= y.s.f)
								s.insert(mp(mp((init + x.f.f) / 2, min(x.f.s, y.f.s)), mp((init + x.f.f) / 2, max(x.f.s, y.f.s))));
						}
						else{
							ll init = y.f.f + (PERM / 2 - dist);
							if((x.f.f - init) % 2 == 0 && (init + x.f.f) / 2 <= x.f.f && 
									(init + x.f.f) / 2 >= y.f.f &&
									(init + x.f.f) / 2 >= x.s.f && (init + x.f.f) / 2 <= y.s.f)
								s.insert(mp(mp((init + x.f.f) / 2, min(x.f.s, y.f.s)), mp((init + x.f.f) / 2, max(x.f.s, y.f.s))));
						}
				}
			}
			if(dist + abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f)
					>= PERM / 2 + abs(p[(a + 1) % N].s - p[a].s + p[(a + 1) % N].f - p[a].f))
				break;
			dist += abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f);
			i++;
		}
		if(i < sz(p)){
			pair<pl, pl> x = mp(p[a], p[(a + 1) % N]);
			pair<pl, pl> y = mp(p[(i + 1) % N], p[(i + 2) % N]);
			if(x.f.s == x.s.s && y.f.s == y.s.s){
				if((x.f.f > x.s.f) != (y.f.f > y.s.f)){
					if(y.f.f > y.s.f){
						ll init = y.f.f - (PERM / 2 - dist - abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f));
						if((init - x.f.f) % 2 == 0 && (init + x.f.f) / 2 >= x.f.f &&
								(init + x.f.f) / 2 <= y.f.f &&
								(init + x.f.f) / 2 <= x.s.f && (init + x.f.f) / 2 >= y.s.f)
							s.insert(mp(mp((init + x.f.f) / 2, min(x.f.s, y.f.s)), mp((init + x.f.f) / 2, max(x.f.s, y.f.s))));
					}
					else{
						ll init = y.f.f + (PERM / 2 - dist - abs(p[(i + 1) % N].s - p[i].s + p[(i + 1) % N].f - p[i].f));
						if((x.f.f - init) % 2 == 0 && (init + x.f.f) / 2 <= x.f.f &&
								(init + x.f.f) / 2 >= y.f.f &&
								(init + x.f.f) / 2 >= x.s.f && (init + x.f.f) / 2 <= y.s.f)
							s.insert(mp(mp((init + x.f.f) / 2, min(x.f.s, y.f.s)), mp((init + x.f.f) / 2, max(x.f.s, y.f.s))));
					}
				}
			}
		}
		dist -= abs(p[(a + 1) % N].s - p[a].s + p[(a + 1) % N].f - p[a].f);
	}//true = start
	priority_queue<pair<pair<ll, bool>, ll>, vector<pair<pair<ll, bool>, ll>>, greater<pair<pair<ll, bool>, ll>>> Q;
	F0R(a, sz(p)){
		pair<pl, pl> temp = mp(p[a], p[(a + 1) % N]);
		if(temp.f.s == temp.s.s){
			if(temp.f > temp.s)
				swap(temp.f, temp.s);
			Q.push(mp(mp(temp.f.f, false), temp.s.s));
			Q.push(mp(mp(temp.s.f, true), temp.s.s));
		}
	}
	Tree<int> c2;
	trav(e, s){
		bool good = false;	
		while(sz(Q) && Q.top().f.f < e.f.f){
			auto temp = Q.top(); Q.pop();
			if(temp.f.s == false)
				c2.insert(temp.s);
			else
				c2.erase(temp.s);
		}
		while(sz(Q) && Q.top().f.f == e.f.f && Q.top().f.s == false){
			auto t2 = Q.top(); Q.pop();
			c2.insert(t2.s);
		}
		int V1 = c2.order_of_key(e.f.s), V2 = c2.order_of_key(e.s.s);
		if(V1 == V2 - 1)
			good = true;
		if(good){
			vpl A1, A;
			vpl B1, B;
			int fst = -1;
			int sec = -1;
			F0R(a, sz(p)){
				if(p[a].s == p[(a + 1) % N].s && p[a].s == e.f.s){
					if(min(p[a].f, p[(a + 1) % N].f) <= e.f.f && max(p[a].f, p[(a + 1) % N].f) >= e.f.f){
						fst = a;
						break;
					}
				}
			}
			F0R(a, sz(p)){
				if(p[a].s == p[(a + 1) % N].s && p[a].s == e.s.s){
					if(min(p[a].f, p[(a + 1) % N].f) <= e.s.f && max(p[a].f, p[(a + 1) % N].f) >= e.s.f){
						sec = a;
						break;
					}
				}
			}
			A1.pb(e.f);
			for(int a = (fst + 1) % N;;a = (a + 1) % N){
				A1.pb(p[a]);
				if(a == sec)
					break;
			}
			A1.pb(e.s);
			B1.pb(e.s);
			for(int a = (sec + 1) % N;;a = (a + 1) % N){
				B1.pb(p[a]);
				if(a == fst)
					break;
			}
			B1.pb(e.f);
			A1.erase(unique(all(A1)), A1.end());
			B1.erase(unique(all(B1)), B1.end());
			F0R(a, sz(A1)){
				if((A1[a].f == A1[(a + 1) % sz(A1)].f && A1[a].s != A1[(a + 1) % sz(A1)].s && 
						A1[(a + 1) % sz(A1)].f != A1[(a + 2) % sz(A1)].f && A1[(a + 1) % sz(A1)].s == A1[(a + 2) % sz(A1)].s)
						|| (A1[a].f != A1[(a + 1) % sz(A1)].f && A1[a].s == A1[(a + 1) % sz(A1)].s && 
						A1[(a + 1) % sz(A1)].f == A1[(a + 2) % sz(A1)].f && A1[(a + 1) % sz(A1)].s != A1[(a + 2) % sz(A1)].s)){
					A.pb(A1[(a + 1) % sz(A1)]);
				}
			}
			F0R(a, sz(B1)){
				if((B1[a].f == B1[(a + 1) % sz(B1)].f && B1[a].s != B1[(a + 1) % sz(B1)].s &&
						B1[(a + 1) % sz(B1)].f != B1[(a + 2) % sz(B1)].f && B1[(a + 1) % sz(B1)].s == B1[(a + 2) % sz(B1)].s)
						|| (B1[a].f != B1[(a + 1) % sz(B1)].f && B1[a].s == B1[(a + 1) % sz(B1)].s &&
						B1[(a + 1) % sz(B1)].f == B1[(a + 2) % sz(B1)].f && B1[(a + 1) % sz(B1)].s != B1[(a + 2) % sz(B1)].s)){
					B.pb(B1[(a + 1) % sz(B1)]);
				}
			}
			bool found = check(A, B);
			if(found){
				if(!flip)
					cout << e.f.f << " " << e.f.s << " " << e.s.f << " " << e.s.s << endl;
				else
					cout << e.f.s << " " << e.f.f << " " << e.s.s << " " << e.s.f << endl;
				return true;
			}
			return false;
		}
	}
	return false;
}

int main(){
    setIO();
	cin >> N;
	vpl poly(N);
	F0R(a, N)
		cin >> poly[a].f >> poly[a].s;
	F0R(a, N)
		PERM += abs(poly[(a + 1) % N].f - poly[a].f)
		+ abs(poly[(a + 1) % N].s - poly[a].s);
	if(PERM % 2 == 1){
		cout << "NO" << endl;
		return 0;
	}
	if(solve(poly))
		return 0;
	F0R(a, N)
		swap(poly[a].f, poly[a].s);
	flip = true;
	if(!solve(poly))
		cout << "NO" << endl;
	// you should actually read the stuff at the bottom
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
    * DON'T GET STUCK ON ONE APPROACH
*/

Compilation message (stderr)

demarcation.cpp: In function 'void setIn(str)':
demarcation.cpp:190:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  190 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
demarcation.cpp: In function 'void setOut(str)':
demarcation.cpp:191:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  191 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 12 / 12
• Subtask 2: 15 / 15
• Subtask 3: 23 / 23
• Subtask 4: 50 / 50