#495915 (C++17) No.1079 まお

• 問題: No.1079 まお
• ユーザー: maroon_kuri
• 提出日時: 2020-06-12 21:56:55
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 336 ms / 2,000 ms
• コード長: 5,980 bytes
• コンパイル時間: 2,547 ms
• コンパイル使用メモリ: 218,884 KB
• 最終ジャッジ日時: 2025-01-11 02:31:14
• ジャッジサーバーID （参考情報）: judge5 / judge2

ファイルパターン	結果
sample	AC * 2
other	AC * 30

ソースコード

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

using ll=long long;
#define int ll

#define rng(i,a,b) for(int i=int(a);i<int(b);i++)
#define rep(i,b) rng(i,0,b)
#define gnr(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define per(i,b) gnr(i,0,b)
#define pb push_back
#define eb emplace_back
#define a first
#define b second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#define si(x) int(x.size())
#ifdef LOCAL
#define dmp(x) cerr<<__LINE__<<" "<<#x<<" "<<x<<endl
#else
#define dmp(x) void(0)
#endif

template<class t,class u> void chmax(t&a,u b){if(a<b)a=b;}
template<class t,class u> void chmin(t&a,u b){if(b<a)a=b;}

template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;

using pi=pair<int,int>;
using vi=vc<int>;

template<class t,class u>
ostream& operator<<(ostream& os,const pair<t,u>& p){
	return os<<"{"<<p.a<<","<<p.b<<"}";
}

template<class t> ostream& operator<<(ostream& os,const vc<t>& v){
	os<<"{";
	for(auto e:v)os<<e<<",";
	return os<<"}";
}

#define mp make_pair
#define mt make_tuple
#define one(x) memset(x,-1,sizeof(x))
#define zero(x) memset(x,0,sizeof(x))
#ifdef LOCAL
void dmpr(ostream&os){os<<endl;}
template<class T,class... Args>
void dmpr(ostream&os,const T&t,const Args&... args){
	os<<t<<" ";
	dmpr(os,args...);
}
#define dmp2(...) dmpr(cerr,__LINE__,##__VA_ARGS__)
#else
#define dmp2(...) void(0)
#endif

using uint=unsigned;
using ull=unsigned long long;

template<class t,size_t n>
ostream& operator<<(ostream&os,const array<t,n>&a){
	return os<<vc<t>(all(a));
}

template<int i,class T>
void print_tuple(ostream&,const T&){
}

template<int i,class T,class H,class ...Args>
void print_tuple(ostream&os,const T&t){
	if(i)os<<",";
	os<<get<i>(t);
	print_tuple<i+1,T,Args...>(os,t);
}

template<class ...Args>
ostream& operator<<(ostream&os,const tuple<Args...>&t){
	os<<"{";
	print_tuple<0,tuple<Args...>,Args...>(os,t);
	return os<<"}";
}

template<class t>
void print(t x,int suc=1){
	cout<<x;
	if(suc==1)
		cout<<"\n";
	if(suc==2)
		cout<<" ";
}

ll read(){
	ll i;
	cin>>i;
	return i;
}

vi readvi(int n,int off=0){
	vi v(n);
	rep(i,n)v[i]=read()+off;
	return v;
}

template<class T>
void print(const vector<T>&v,int suc=1){
	rep(i,v.size())
		print(v[i],i==int(v.size())-1?suc:2);
}

string readString(){
	string s;
	cin>>s;
	return s;
}

template<class T>
T sq(const T& t){
	return t*t;
}

//#define CAPITAL
void yes(bool ex=true){
	#ifdef CAPITAL
	cout<<"YES"<<"\n";
	#else
	cout<<"Yes"<<"\n";
	#endif
	if(ex)exit(0);
}
void no(bool ex=true){
	#ifdef CAPITAL
	cout<<"NO"<<"\n";
	#else
	cout<<"No"<<"\n";
	#endif
	if(ex)exit(0);
}
void possible(bool ex=true){
	#ifdef CAPITAL
	cout<<"POSSIBLE"<<"\n";
	#else
	cout<<"Possible"<<"\n";
	#endif
	if(ex)exit(0);
}
void impossible(bool ex=true){
	#ifdef CAPITAL
	cout<<"IMPOSSIBLE"<<"\n";
	#else
	cout<<"Impossible"<<"\n";
	#endif
	if(ex)exit(0);
}

constexpr ll ten(int n){
	return n==0?1:ten(n-1)*10;
}

const ll infLL=LLONG_MAX/3;

#ifdef int
const int inf=infLL;
#else
const int inf=INT_MAX/2-100;
#endif

int topbit(signed t){
	return t==0?-1:31-__builtin_clz(t);
}
int topbit(ll t){
	return t==0?-1:63-__builtin_clzll(t);
}
int botbit(signed a){
	return a==0?32:__builtin_ctz(a);
}
int botbit(ll a){
	return a==0?64:__builtin_ctzll(a);
}
int popcount(signed t){
	return __builtin_popcount(t);
}
int popcount(ll t){
	return __builtin_popcountll(t);
}
bool ispow2(int i){
	return i&&(i&-i)==i;
}
ll mask(int i){
	return (ll(1)<<i)-1;
}

bool inc(int a,int b,int c){
	return a<=b&&b<=c;
}

template<class t> void mkuni(vc<t>&v){
	sort(all(v));
	v.erase(unique(all(v)),v.ed);
}

ll rand_int(ll l, ll r) { //[l, r]
	#ifdef LOCAL
	static mt19937_64 gen;
	#else
	static mt19937_64 gen(chrono::steady_clock::now().time_since_epoch().count());
	#endif
	return uniform_int_distribution<ll>(l, r)(gen);
}

template<class t>
void myshuffle(vc<t>&a){
	rep(i,si(a))swap(a[i],a[rand_int(0,i)]);
}

template<class t>
int lwb(const vc<t>&v,const t&a){
	return lower_bound(all(v),a)-v.bg;
}

//VERIFY: yosupo
//KUPC2017J
//AOJDSL1A
//without rank
struct unionfind{
	vi p,s;
	int c;
	unionfind(int n):p(n,-1),s(n,1),c(n){}
	int find(int a){
		return p[a]==-1?a:(p[a]=find(p[a]));
	}
	//set b to a child of a
	bool unite(int a,int b){
		a=find(a);
		b=find(b);
		if(a==b)return false;
		p[b]=a;
		s[a]+=s[b];
		c--;
		return true;
	}
	bool same(int a,int b){
		return find(a)==find(b);
	}
	int sz(int a){
		return s[find(a)];
	}
};

void piadd(pi&a,pi b){
	a.a+=b.a;
	a.b+=b.b;
}

void waf(map<int,pi>&a,map<int,pi>&b){
	if(si(a)<si(b))swap(a,b);
	for(auto kv:b){
		piadd(a[kv.a],kv.b);
	}
}

int relka(pi a,pi b){
	dmp2(a,b);
	return a.a*b.b-a.b*b.a+a.a*b.a;
}

int cnt(int k,const map<int,pi>&a,const map<int,pi>&b){
	int res=0;
	if(si(a)<si(b)){
		for(auto kv:a){
			auto itr=b.find(k-kv.a);
			if(itr!=b.ed){
				res+=relka(kv.b,itr->b);
			}
		}
	}else{
		for(auto kv:b){
			auto itr=a.find(k-kv.a);
			if(itr!=a.ed){
				res+=relka(itr->b,kv.b);
			}
		}
	}
	return res;
}

signed main(){
	cin.tie(0);
	ios::sync_with_stdio(0);
	cout<<fixed<<setprecision(20);
	
	int n,k;cin>>n>>k;
	vi a=readvi(n);
	
	vc<map<int,pi>> cur(n);
	rep(i,n)cur[i][a[i]]=pi(1,i);
	vi did(n);
	unionfind uf(n);
	
	auto mrg=[&](int i){
		assert(did[i]);
		assert(did[i+1]);
		int j=i+1;
		i=uf.find(i);
		assert(uf.find(j)==j);
		waf(cur[i],cur[j]);
		uf.unite(i,j);
	};
	
	auto meld=[&](int i){
		assert(!did[i]);
		did[i]=1;
		if(i>0&&did[i-1])
			mrg(i-1);
		if(i+1<n&&did[i+1])
			mrg(i);
	};
	
	
	map<int,vi> ls;
	rep(i,n)ls[-a[i]].pb(i);
	
	int ans=0;
	
	for(auto kv:ls){
		for(auto p:kv.b){
			if(p>0&&did[p-1]){
				ans+=cnt(k,cur[uf.find(p-1)],cur[p]);
			}
			if(p+1<n&&did[p+1]){
				ans+=cnt(k,cur[p],cur[uf.find(p+1)]);
			}
			if(p>0&&did[p-1]&&p+1<n&&did[p+1]){
				if(p==6){
					dmp(0);
					dmp(uf.find(p-1));
					dmp(uf.find(p+1));
				}
				ans+=cnt(k,cur[uf.find(p-1)],cur[uf.find(p+1)]);
			}
			if(a[p]*2==k)ans++;
		}
		for(auto p:kv.b){
			meld(p);
		}
	}
	
	print(ans);
}