Submission #265387

#	Time	Username	Problem	Language	Result	Execution time	Memory
265387		rqi	Dancing Elephants (IOI11_elephants)	C++14	100 / 100	3167 ms	37248 KiB

elephants

#include "elephants.h"
#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef double db; 
typedef string str; 

typedef pair<int,int> pi;
typedef pair<ll,ll> pl; 
typedef pair<db,db> pd; 

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

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

#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; 
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 

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; } 
constexpr int pct(int x) { return __builtin_popcount(x); } 
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
ll half(ll x) { return fdiv(x,2); }

template<class T, class U> T fstTrue(T lo, T hi, U f) { 
	// note: if (lo+hi)/2 is used instead of half(lo+hi) then this will loop infinitely when lo=hi
	hi ++; assert(lo <= hi); // assuming f is increasing
	while (lo < hi) { // find first index such that f is true 
		T mid = half(lo+hi);
		f(mid) ? hi = mid : lo = mid+1; 
	} 
	return lo;
}
template<class T, class U> 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 = half(lo+hi+1);
		f(mid) ? lo = mid : hi = mid-1;
	} 
	return lo;
}
template<class T> void remDup(vector<T>& v) { 
	sort(all(v)); v.erase(unique(all(v)),end(v)); }

// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);

template<class T> 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); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }

template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,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
}
template<class A> str ts(complex<A> 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; }
template<class A, class B> str ts(pair<A,B> p);
template<class T> 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
}
template<class A, class B> str ts(pair<A,B> p) {
	#ifdef LOCAL
		return "("+ts(p.f)+", "+ts(p.s)+")"; 
	#else
		return ts(p.f)+" "+ts(p.s);
	#endif
}

// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { 
	pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) { 
	pr(h); if (sizeof...(t)) pr(" "); ps(t...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
	cerr << ts(h); if (sizeof...(t)) cerr << ", ";
	DBG(t...); }
#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
}

/**
 * Description: Link-Cut Tree. Given a function $f(1\ldots N)\to 1\ldots N,$ 
 	* evaluates $f^b(a)$ for any $a,b.$ \texttt{sz} is for path queries; 
 	* \texttt{sub}, \texttt{vsub} are for subtree queries. \texttt{x->access()} 
 	* brings \texttt{x} to the top and propagates it; its left subtree will be 
 	* the path from \texttt{x} to the root and its right subtree will be empty. 
 	* Then \texttt{sub} will be the number of nodes in the connected component
 	* of \texttt{x} and \texttt{vsub} will be the number of nodes under \texttt{x}.
 	* Use \texttt{makeRoot} for arbitrary path queries.
 * Time: O(\log N)
 * Usage: FOR(i,1,N+1)LCT[i]=new snode(i); link(LCT[1],LCT[2],1);
 * Source: Dhruv Rohatgi, Eric Zhang
	* https://sites.google.com/site/kc97ble/container/splay-tree/splaytree-cpp-3
	* https://codeforces.com/blog/entry/67637
 * Verification: (see README for links)
	* ekzhang Balanced Tokens
	* Dynamic Tree Test (Easy)
	* https://probgate.org/viewproblem.php?pid=578 (The Applicant)
 */

typedef struct snode* sn;
struct snode { //////// VARIABLES
	sn p, c[2]; // parent, children
	bool flip = 0; // subtree flipped or not
	int val, sz; // value in node, # nodes in current splay tree
	int sub, vsub = 0; // vsub stores sum of virtual children
	int vsum;
	snode(int _val) : val(_val) {
		p = c[0] = c[1]; calc(); }
	friend int getSz(sn x) { return x?x->sz:0; }
	friend int getSub(sn x) { return x?x->sub:0; }
	friend int getVsum(sn x) { return x?x->vsum:0; }
	void prop() { // lazy prop
		if (!flip) return;
		swap(c[0],c[1]); flip = 0;
		F0R(i,2) if (c[i]) c[i]->flip ^= 1;
	}
	void calc() { // recalc vals
		F0R(i,2) if (c[i]) c[i]->prop();
		sz = 1+getSz(c[0])+getSz(c[1]);
		sub = 1+getSub(c[0])+getSub(c[1])+vsub;
		vsum = val+getVsum(c[0])+getVsum(c[1]);
	}
	//////// SPLAY TREE OPERATIONS
	int dir() {
		if (!p) return -2;
		F0R(i,2) if (p->c[i] == this) return i;
		return -1; // p is path-parent pointer
	} // -> not in current splay tree
	// test if root of current splay tree
	bool isRoot() { return dir() < 0; } 
	friend void setLink(sn x, sn y, int d) {
		if (y) y->p = x;
		if (d >= 0) x->c[d] = y; }
	void rot() { // assume p and p->p propagated
		assert(!isRoot()); int x = dir(); sn pa = p;
		setLink(pa->p, this, pa->dir());
		setLink(pa, c[x^1], x); setLink(this, pa, x^1);
		pa->calc(); calc();
	}
	void splay() {
		while (!isRoot() && !p->isRoot()) {
			p->p->prop(), p->prop(), prop();
			dir() == p->dir() ? p->rot() : rot();
			rot();
		}
		if (!isRoot()) p->prop(), prop(), rot();
		prop();
	}
	sn fbo(int b) { // find by order
		prop(); int z = getSz(c[0]); // of splay tree
		if (b == z) { splay(); return this; }
		return b < z ? c[0]->fbo(b) : c[1] -> fbo(b-z-1);
	}
	//////// BASE OPERATIONS
	void access() { // bring this to top of tree, propagate
		for (sn v = this, pre = NULL; v; v = v->p) {
			v->splay(); // now switch virtual children
			if (pre) v->vsub -= pre->sub;
			if (v->c[1]) v->vsub += v->c[1]->sub;
			v->c[1] = pre; v->calc(); pre = v;
		}
		splay(); assert(!c[1]); // right subtree is empty
	}
	void makeRoot() { 
		access(); flip ^= 1; access(); assert(!c[0] && !c[1]); }
	//////// QUERIES
	friend sn lca(sn x, sn y) {
		if (x == y) return x;
		x->access(), y->access(); if (!x->p) return NULL;
		x->splay(); return x->p?:x; // y was below x in latter case
	} // access at y did not affect x -> not connected
	friend bool connected(sn x, sn y) { return lca(x,y); } 
	// # nodes above
	int distRoot() { access(); return getSz(c[0]); } 
	sn getRoot() { // get root of LCT component
		access(); sn a = this; 
		while (a->c[0]) a = a->c[0], a->prop();
		a->access(); return a;
	}
	sn getPar(int b) { // get b-th parent on path to root
		access(); b = getSz(c[0])-b; assert(b >= 0);
		return fbo(b);
	} // can also get min, max on path to root, etc
	//////// MODIFICATIONS
	void set(int v) { access(); val = v; calc(); } 
	friend void link(sn x, sn y, bool force = 0) { 
		assert(!connected(x,y)); 
		if (force) y->makeRoot(); // make x par of y
		else { y->access(); assert(!y->c[0]); }
		x->access(); setLink(y,x,0); y->calc();
	}
	friend void cut(sn y) { // cut y from its parent
		y->access(); assert(y->c[0]);
		y->c[0]->p = NULL; y->c[0] = NULL; y->calc(); }
	friend void cut(sn x, sn y) { // if x, y adj in tree
		x->makeRoot(); y->access(); 
		assert(y->c[0] == x && !x->c[0] && !x->c[1]); cut(y); }
};
sn LCT[400005];

const int mx = 150005;
int N, L;
int X[mx];
int par[mx];
set<pi> m;
int M;

void init(int _N, int _L, int _X[])
{
	N = _N;
	L = _L;
	M = N+5;
	for(int i = 0; i < N; i++){
		X[i] = _X[i];
		m.ins(mp(X[i], i));
	}
	X[N] = 2*MOD;
	m.ins(mp(2*MOD, N));
	LCT[N] = new snode(0);

	for(int i = 0; i < N; i++){
		LCT[i] = new snode(0);
		LCT[i+M] = new snode(0);
		link(LCT[i+M], LCT[i], 1);
		//dbg(i+M, i);
	}
	//dbg(N, M);
	for(int i = 0; i < N; i++){
		int to = (m.lb(mp(X[i]+L+1, 0)))->s;
		int nex = (next(m.find(mp(X[i], i))))->s;
		//dbg(i, to, nex);
		if(nex != N && (m.lb(mp(X[nex]+L+1, 0)))->s == to){
			LCT[i+M]->set(0);
			link(LCT[nex], LCT[i+M], 1);
			par[i] = nex;
			//dbg(nex, i+M);
		}
		else{
			LCT[i+M]->set(1);
			link(LCT[to], LCT[i+M], 1);
			par[i] = to;
			//dbg(to, i+M);
		}
	}
	
}

int spec;

void upd(int i){
	if(i == -1) return;
	//dbg(i);
	// for(int i = 0; i < N; i++){
	// 	dbg(i, par[i]);
	// }
	// dbg(i+M, par[i]);
	// dbg(connected(LCT[i+M], LCT[par[i]]));	
	// dbg(i+M, par[i]);

	if(spec != i) cut(LCT[i+M], LCT[par[i]]);
	//dbg("cut", i+M, par[i]);

	int to = (m.lb(mp(X[i]+L+1, 0)))->s;
	int nex = (next(m.find(mp(X[i], i))))->s;
	//dbg(to, nex);

	if(nex != N && (m.lb(mp(X[nex]+L+1, 0)))->s == to){
		LCT[i+M]->set(0);
		//dbg(nex, i+M);
		link(LCT[nex], LCT[i+M], 1);
		
		par[i] = nex;
	}
	else{
		LCT[i+M]->set(1);
		//dbg(to, i+M);
		link(LCT[to], LCT[i+M], 1);
		
		par[i] = to;
	}
}

int update(int i, int y)
{
	spec = i;
	//dbg(i, y);
	//erase from lct
	int prv1 = -1, prv2 = -1;

	if(m.find(mp(X[i], i)) != m.begin()){
		prv1 = (prev(m.find(mp(X[i], i))))->s;
	}
	auto it = m.lb(mp(X[i]-L, 0));
	if(it != m.begin()){
		prv2 = prev(it)->s;
	}
	//dbg(prv1, prv2);
	m.erase(mp(X[i], i));
	cut(LCT[i+M], LCT[par[i]]);
	upd(prv1);
	upd(prv2);

	X[i] = y;
	//add to lct
	m.ins(mp(X[i], i));
	prv1 = -1, prv2 = -1;
	if(m.find(mp(X[i], i)) != m.begin()){
		prv1 = (prev(m.find(mp(X[i], i))))->s;
	}
	it = m.lb(mp(X[i]-L, 0));
	if(it != m.begin()){
		prv2 = prev(it)->s;
	}
	
	//dbg(prv1, prv2, i);
	upd(prv1);
	upd(prv2);
	upd(i);

	LCT[N]->makeRoot();
	int beg = (m.begin())->s;
	LCT[beg]->access();
	int ans = getVsum(LCT[beg]);

	return ans;
}

Compilation message (stderr)

elephants.cpp: In function 'void setIn(str)':
elephants.cpp:169:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  169 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
elephants.cpp: In function 'void setOut(str)':
elephants.cpp:170:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  170 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
elephants.cpp: In constructor 'snode::snode(int)':
elephants.cpp:208:17: warning: '*<unknown>.snode::c[1]' is used uninitialized in this function [-Wuninitialized]
  208 |   p = c[0] = c[1]; calc(); }
      |              ~~~^

• Subtask 1: 10 / 10
• Subtask 2: 16 / 16
• Subtask 3: 24 / 24
• Subtask 4: 47 / 47
• Subtask 5: 3 / 3