Submission #406018

#	Time	Username	Problem	Language	Result	Execution time	Memory
406018		oolimry	The short shank; Redemption (BOI21_prison)	C++17	100 / 100	798 ms	280892 KiB

prison

#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int) x.size())
#define show(x) cerr << #x << " is " << x << endl;
#define show2(x, y) cerr << #x << " is " << x << ", " << #y << " is " << y << endl;
#define show3(x, y, z) cerr << #x << " is " << x << ", " << #y << " is " << y << ", " << #z << " is " << z << endl;
#define l first
#define r second
typedef long long lint;
typedef pair<lint, lint> ii;

lint arr[2000005];
int p[2000005];
vector<int> child[2000005];
int vis[2000005];
ii maxh[2000005];
int cnt = 0;

void dfs(int u){
	maxh[u] = ii(0, u);
	for(int v : child[u]){
		dfs(v);
		maxh[u] = max(maxh[u], maxh[v]);
	}
	maxh[u].first += 1;
}

priority_queue<ii> pq;

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	
	lint n, S, T; cin >> n >> S >> T;
	for(int i = 1;i <= n;i++) cin >> arr[i];
	
	lint ans = n;
	vector<ii> useful;
	vector<ii> ranges;
	for(int i = 1;i <= n;i++){
		if(arr[i] <= T){
			int reach = min(n, i+T-arr[i]);
			//show2(i, reach);
			while(not useful.empty()){
				if(useful.back().first <= reach) useful.pop_back();
				else break;
			}
			useful.push_back(ii(reach,i));
		}
		else{
			auto it = lower_bound(all(useful), ii(i, -1), greater<ii>());
			if(it != useful.begin()){
				it--;
				ranges.push_back(ii(it->second,i));
			}
			else{
				ans--;
			}
		}
	}
	
	sort(all(ranges), [&](ii a, ii b){
		if(a.l  == b.l) return a.r > b.r;
		else return a.l < b.l;
	});
	
	stack<ii> ST;
	for(ii R : ranges){
		while(not ST.empty()){
			if(ST.top().first <= R.first) ST.pop();
			else break;
		}
		cnt++;
		if(not ST.empty()) p[cnt] = ST.top().second;
		ST.push(ii(R.r, cnt));
	}
	for(int i = 1;i <= cnt;i++) child[p[i]].push_back(i);
	dfs(0);
	
	pq.push(maxh[0]);
	//for(int i = 0;i <= cnt;i++){
	//	show2(maxh[i].first, maxh[i].second);
	//}
	while(S--){
		if(pq.empty()) break;
		ii t = pq.top(); pq.pop();
		ans -= t.first;
		int u = t.second;
		//show2(t.first, u);
		
		while(not vis[u]){
			int par = p[u];
			//show2(u,par);
			vis[u] = true;
			if(vis[par]) break;
			for(int v : child[par]){
				if(v != u){
					pq.push(maxh[v]);
					//show3(u,par,v);
				}
			}
			u = par;			
		}
	}
	
	///potenially ans++ here cause of 0
	ans++;
	cout << ans;
}

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 20 / 20