Submission #1068116

#	Time	Username	Problem	Language	Result	Execution time	Memory
1068116		LittleOrange	Rectangles (IOI19_rect)	C++17	72 / 100	5025 ms	206144 KiB

rect

#include "rect.h"
#include<bits/stdc++.h>
using namespace std;
using ll = int;
using lll = long long;
const ll maxn = 2500;
struct BIT{
	ll n;
	vector<ll> a;
	BIT(ll N):n(N),a(N+1,0){}
	void add(ll i, ll v){
		for(;i<=n;i+=i&-i) a[i] += v;
	}
	ll get(ll i){
		ll x = 0;
		for(;i>0;i-=i&-i) x += a[i];
		return x;
	}
};
struct dsu{
	vector<ll> p;
	dsu(ll N):p(N,-1){}
	ll g(ll i){
		return p[i]<0?i:p[i] = g(p[i]);
	}
	bool m(ll a,ll b){
		a = g(a),b = g(b);
		if (a==b) return false;
		if (p[a]>p[b]) swap(a,b);
		p[a] += p[b];
		p[b] = a;
		return true;
	}
};

long long count_rectangles(std::vector<std::vector<int> > a) {
	ll n = a.size(), m = a[0].size();
	if (n<3||m<3) return 0;
	ll sub6 = 1;
	for(auto &o : a) for(ll &i : o) if (i>1) sub6 = 0;
	if (0&&sub6){
		dsu d(n*m);
		for(ll i = 1;i<n-1;i++){
			for(ll j = 1;j<m-1;j++){
				if(i>1&&!a[i][j]&&!a[i-1][j]){
					d.m((i)*m+(j),(i-1)*m+(j));
				}
				if(j>1&&!a[i][j]&&!a[i][j-1]){
					d.m((i)*m+(j),(i)*m+(j-1));
				}
			}
		}
		vector<ll> gs;
		for(ll i = 1;i<n-1;i++){
			for(ll j = 1;j<m-1;j++){
				if(!a[i][j]){
					gs.push_back(d.g((i)*m+(j)));
				}
			}
		}
		sort(gs.begin(),gs.end());
		gs.erase(unique(gs.begin(),gs.end()),gs.end());
		ll gc = gs.size();
		vector<vector<pair<ll,ll>>> ps(gc);
		for(ll i = 1;i<n-1;i++){
			for(ll j = 1;j<m-1;j++){
				if(!a[i][j]){
					ll p = d.g((i)*m+(j));
					ll idx = lower_bound(gs.begin(),gs.end(),p)-gs.begin();
					ps[idx].push_back({i,j});
				}
			}
		}
		ll ans = 0;
		for(auto &o : ps){
			ll x1 = o[0].first, x2=o[0].first, y1=o[0].second, y2=o[0].second;
			for(auto [x,y] : o){
				x1 = min(x,x1);
				x2 = max(x,x2);
				y1 = min(y,y1);
				y2 = max(y,y2);
			}
			ll req = (x2-x1+1)*(y2-y1+1);
			if (req==o.size()) ans++;
		}
		return ans;
	}
	vector<vector<pair<ll,ll>>> row(n),col(m);
	for(ll i = 0;i<n;i++){
		vector<pair<ll,ll>> st;
		for(ll j = 0;j<m;j++){
			while(st.size()&&st.back().first<a[i][j]){
				if(j>st.back().second+1)row[i].push_back({st.back().second,j});
				st.pop_back();
			}
			if(st.size()){
				if(j>st.back().second+1)row[i].push_back({st.back().second,j});
			}
			if (st.size()&&st.back().first==a[i][j]) st.pop_back();
			st.push_back({a[i][j],j});
		}
	}
	for(ll j = 0;j<m;j++){
		vector<pair<ll,ll>> st;
		for(ll i = 0;i<n;i++){
			while(st.size()&&st.back().first<a[i][j]){
				if(i>st.back().second+1)col[j].push_back({st.back().second,i});
				st.pop_back();
			}
			if(st.size()){
				if(i>st.back().second+1)col[j].push_back({st.back().second,i});
			}
			if (st.size()&&st.back().first==a[i][j]) st.pop_back();
			st.push_back({a[i][j],i});
		}
	}
	for(auto &o : row) sort(o.begin(),o.end());
	for(auto &o : col) sort(o.begin(),o.end());
	vector<vector<ll>> down(n,vector<ll>(m,0)),up(n,vector<ll>(m,n));
	for(ll i = 0;i<m;i++){
		for(auto [l,r] : col[i]){
			down[l][i] = r;
			up[l][i] = min(up[l][i],r);
		}
	}
	lll ans = 0;
	for(ll r1 = 1;r1<n-1;r1++){
		vector<pair<ll,ll>> cur = row[r1];
		vector<pair<ll,ll>> nw;
		BIT t(m);
		vector<vector<pair<ll,ll>>> ops(n);
		if (sub6) for(ll i = 0;i<m;i++) {
			ops[max(up[r1-1][i]-1,r1)].push_back({i+1,1});
			ops[down[r1-1][i]].push_back({i+1,1});
		}
		for(ll r2 = r1;r2<n-1;r2++){
			if (sub6) for(auto [i,v] : ops[r2]){
				t.add(i,v);
			}
			if(r2>r1){
				for(auto &o : cur){
					if (binary_search(row[r2].begin(),row[r2].end(),o)){
						nw.push_back(o);
					}
				}
				nw.swap(cur);
				nw.clear();
			}
			if (sub6){
				for(auto &o : cur){
					if (t.get(o.second)-t.get(o.first+1)==(o.second-o.first-1)) ans++;
				}
			}else{
				pair<ll,ll> t = {r1-1,r2+1};
				vector<ll> ok(m,0);
				for(ll i = 0;i<m;i++) ok[i] = down[r1-1][i]>r2&&up[r1-1][i]-1<=r2&&binary_search(col[i].begin(),col[i].end(),t);
				vector<ll> p(m+1,0);
				for(ll i = 0;i<m;i++) p[i+1] = p[i]+ok[i];
				for(auto &o : cur){
					if (p[o.second]-p[o.first+1]==(o.second-o.first-1)) ans++;
				}
			}
		}
	}
	return ans;
}

Compilation message (stderr)

rect.cpp: In function 'long long int count_rectangles(std::vector<std::vector<int> >)':
rect.cpp:84:11: warning: comparison of integer expressions of different signedness: 'll' {aka 'int'} and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |    if (req==o.size()) ans++;
      |        ~~~^~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 22 / 22
• Subtask 5: 10 / 10
• Subtask 6: 13 / 13
• Subtask 7: 0 / 28