Submission #55292

#	Time	Username	Problem	Language	Result	Execution time	Memory
55292		ksun48	Cultivation (JOI17_cultivation)	C++14	30 / 100	65 ms	700 KiB

cultivation

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

LL r, c, n;
vector<pair<LL,LL> > seeds;
const LL INF = 2100100100;
LL best = INF;
set<LL> tried;
void tryxfast(LL x){
	if(x < 0 || tried.find(x) != tried.end()){
		return;
	}
	tried.insert(x);

	map<LL, vector<pair<LL, LL> > > events;
	for(pair<LL,LL> z : seeds){
		events[z.first - x].push_back({0, z.second}); // ins
		events[z.first + 1].push_back({1, z.second}); // del
	}

	vector<LL> pos;
	vector<LL> ups;
	vector<LL> downs;
	vector<LL> totals;

	multiset<LL> grass;
	grass.insert(-1);
	grass.insert(c);
	multiset<LL> diffs;
	diffs.insert(-(c+1));
	for(auto tt : events){
		for(pair<LL,LL> event : tt.second){
			LL a = event.second;
			if(event.first == 0){
				grass.insert(a);
			}
			LL a1 = *(--grass.find(a));
			LL a2 = *(++grass.find(a));
			if(event.first == 0){
				diffs.erase(diffs.find(a1-a2));
				diffs.insert(a1-a);
				diffs.insert(a-a2);
			} else if(event.first == 1){
				diffs.erase(diffs.find(a1-a));
				diffs.erase(diffs.find(a-a2));
				diffs.insert(a1-a2);
			}
			if(event.first == 1){
				grass.erase(grass.find(a));
			}
		}
		pos.push_back(tt.first);
		totals.push_back( -*diffs.begin() );
		ups.push_back( *(++grass.begin()) - 0 );
		downs.push_back( c-1 - *(--(--grass.end())) );
	}
	// two pointers: 
	LL j = 0;
	multiset<LL> upset;
	multiset<LL> downset;
	multiset<LL> totalset;
	for(LL i = 0; i < pos.size(); i++){
		while(j < pos.size() && pos[j] <= pos[i] + r - 1){
			upset.insert(-ups[j]);
			downset.insert(-downs[j]);
			totalset.insert(-totals[j]);
			j++;
		}
		LL total = -*totalset.begin();
		if(total < c+1){
			best = min(best, max(-*upset.begin() + -*downset.begin(), total - 1) + x);
		}
		upset.erase(upset.find(-ups[i]));
		downset.erase(downset.find(-downs[i]));
		totalset.erase(totalset.find(-totals[i]));
	}
}
int main(){
	cin.sync_with_stdio(0); cin.tie(0);
	cin >> r >> c >> n;
	for(LL i = 0; i < n; i++){
		LL s, e;
		cin >> s >> e;
		s--; e--;
		seeds.push_back({s,e});
	}
	sort(seeds.begin(), seeds.end());
	for(LL i = 0; i < n; i++){
		for(LL j = 0; j < n; j++){
			tryxfast(seeds[i].first + r-1 - seeds[j].first);
			tryxfast(seeds[i].first -   1 - seeds[j].first);
		}
	}
	cout << best << '\n';
}

Compilation message (stderr)

cultivation.cpp: In function 'void tryxfast(LL)':
cultivation.cpp:63:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(LL i = 0; i < pos.size(); i++){
                ~~^~~~~~~~~~~~
cultivation.cpp:64:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(j < pos.size() && pos[j] <= pos[i] + r - 1){
         ~~^~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 0 / 30
• Subtask 5: 0 / 20
• Subtask 6: 0 / 20