Submission #331476

#	Time	Username	Problem	Language	Result	Execution time	Memory
331476		aloo123	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	191 ms	24544 KiB

fancyfence

#include <bits/stdc++.h>
using namespace std;
 
using ll = 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 ld PI = acos((ld)-1);
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
}
 
#define int ll
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; // for every grid problem!!
const int N = 2e5+5;
const int LOG = 25;

int comp(int n){
	int ans  =n;ans*=(n+1);
	ans>>=1ll;
	ans%=MOD;
	return ans;
}
bool is_part[N];
int h[N],w[N],min_h[N],sum_w[N];
int val[N];
int cur = 0;
struct dsu{
	int sz[N];
	int par[N];
	void init(int u){
		is_part[u]=1;
		sz[u] = 1;
		par[u] = u;
		min_h[u] = h[u];
		sum_w[u] = (sum_w[u] + w[u])%MOD;
		int x = comp(h[u]);
		x = (x * comp(w[u]))%MOD;
		cur = (cur + x)%MOD;		
		val[u] = x;
	}
	int find_par(int u){
		if(u==par[u])return u;
		return par[u]=find_par(par[u]);
	}
	void unite(int u,int v){
		u = find_par(u),v= find_par(v);
		if(u == v)return;
		if(sz[u]>sz[v])swap(u,v);

		min_h[v] = min(min_h[v],min_h[u]);
		sum_w[v] = (sum_w[v] + sum_w[u])%MOD;
		

		sz[v]+=sz[u];
		par[u] =v;
		sum_w[u] = 0;
		min_h[u]=INF;
		sz[u]=0;
	}
	void unite2(int u,int v,int H){
		u = find_par(u),v = find_par(v);
		if(u == v) return;
		// if(sz[u]>sz[v])swap(u,v);
		int x = comp(H);
		x = (x * w[u])%MOD;
		x = (x * sum_w[v])%MOD;
		cur = (cur + x)%MOD;

		min_h[v] = min(min_h[v],H);
		sum_w[v] = (sum_w[v] + sum_w[u])%MOD;

		sz[v] += sz[u];
		par[u] = v;
		sum_w[u] = 0;
		min_h[u] = INF;
		sz[u] = 0;

	}
};
dsu g;
map<int,vl> m;
void solve(){
	int n;
	re(n);
	set<int> s;
	FOR(i,1,n+1){
		re(h[i]);
		s.ins(h[i]);
		m[h[i]].pb(i);
	}
	FOR(i,1,n+1){
		re(w[i]);
	}

	vl v;
	trav(x,s) v.pb(x);	
	ROF(i,0,sz(v)){
		int x = v[i];
		// take all h[i] >= x
		trav(id,m[x]){
			g.init(id);
			bool b = 1;
			b &= (id != 1 && is_part[id-1]);
			b &= (id != n && is_part[id+1]);
			if(!b){
				if(id != 1 && is_part[id-1]) g.unite2(id,id-1,h[id]);
				if(id != n && is_part[id+1]) g.unite2(id,id+1,h[id]);
				continue;
			}
			int lol = g.find_par(id-1);
			int lol2 = g.find_par(id+1);
			// compute rectangles in id-1 and id
			int cc = comp(x);
			cc = (w[id] * cc)%MOD;
			cc = (sum_w[lol] * cc)%MOD;
			cur = (cur + cc)%MOD;
			//------

			// compute rectangles in id and id+1
			cc = comp(x);
			cc = (w[id] * cc)%MOD;
			cc = (sum_w[lol2] * cc)%MOD;
			cur = (cur + cc)%MOD;
			//-------

			// compute rectangles in id-1 and id+1
			cc = comp(x);
			cc = (sum_w[lol] * cc)%MOD;
			cc = (sum_w[lol2] * cc)%MOD;
			cur = (cur + cc)%MOD;
			//------			
			
			g.unite(id,id-1);
			g.unite(id,id+1);
		}
	}


	ps(cur);
}
signed main() {
	setIO();	
	// you should actually read the stuff at the bottom
	int t=1;
	// re(t);
	while(t--){
		solve();
	}
}
 
/* stuff you should look for
	* read the probem 3 more times in case of WA :)
	* 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)

fancyfence.cpp: In function 'void setIn(str)':
fancyfence.cpp:181:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  181 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
      |                     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
fancyfence.cpp: In function 'void setOut(str)':
fancyfence.cpp:182:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  182 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
      |                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 18 / 18
• Subtask 7: 27 / 27