Submission #1075654

#	Time	Username	Problem	Language	Result	Execution time	Memory
1075654		GrindMachine	Sprinklers (CEOI24_sprinklers)	C++17	0 / 100	138 ms	13468 KiB

Main

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

typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define conts continue
#define ff first
#define ss second
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define sz(a) (int)a.size()

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i) 
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &x, T y){
	x = min(x,y);
}

template<typename T>
void amax(T &x, T y){
	x = max(x,y);
}

template<typename A,typename B>
string to_string(pair<A,B> p);

string to_string(const string &s){
	return "'"+s+"'";
}

string to_string(const char *s){
	return to_string((string)s);
}

string to_string(bool b){
	return b?"true":"false";
}

template<typename A>
string to_string(A v){
	string res = "{";
	trav(x,v){
		res += to_string(x)+",";
	}
	if(res.back() == ',') res.pop_back();
	res += "}";
	return res;
}

template<typename A,typename B>
string to_string(pair<A,B> p){
	return "("+to_string(p.ff)+","+to_string(p.ss)+")";
}

#define debug(x) cout << #x << " = "; cout << to_string(x) << endl

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = 1e9 + 5;
const ll inf2 = (ll)1e18 + 5;

void solve(int test_case){
	ll n,m; cin >> n >> m;
	vector<ll> a(n+5), b(m+5);
	rep1(i,n) cin >> a[i];
	rep1(i,m) cin >> b[i];
	// sort(a.begin()+1,a.begin()+n+1);
	// sort(b.begin()+1,b.begin()+m+1);

	rep1(i,m){
		if(binary_search(a.begin()+1,a.begin()+n+1,b[i])){
			b[i] = -1;
		}
	}

	vector<array<ll,3>> c;
	rep1(i,n) c.pb({a[i],i,1});
	rep1(i,m){
		if(b[i] != -1){
			c.pb({b[i],i,2});
		}
	}
	sort(all(c));
	ll siz = sz(c);

	vector<char> ans(n+5,'?');

	auto ok = [&](ll mid, bool construct){
		vector<ll> dp1(m+5,-inf2);
		dp1[0] = 0;
		map<ll,ll> par[siz+5];
		ll ind = -1;

		for(auto [x,i,t] : c){
			ind++;
			if(t == 1){
				pll mx = {-inf2,-1};

				rep1(j,m){
					if(b[j] > a[i]) break;
					if(dp1[j] < 0) conts;

					// turn left
					if(b[j] >= a[i]-mid){
						pll px = {dp1[j],j};
						amax(mx,px);
					}

					// turn right
					dp1[j] = a[i]+mid;
				}

				// turn right
				if(dp1[0] >= 0){
					dp1[0] = a[i]+mid;
				}

				// turn left
				if(mx.ff > dp1[0]){
					dp1[0] = mx.ff;
					par[ind][0] = mx.ss;
				}
			}
			else{
				if(dp1[0] >= x) conts;
				dp1[i] = dp1[0];
				dp1[0] = -inf2;
				par[ind][i] = 0;
			}
		}

		if(construct){
			assert(dp1[0] >= 0);

			ll j = 0;
			rev(ind,siz-1,0){
				if(par[ind].count(j)){
					ll j2 = par[ind][j];
					if(c[ind][2] == 1){
						ll i = c[ind][1];
						assert(j == 0 and j2 > j);
						ans[i] = 'L';
					}
					j = j2;
				}
				else{
					if(c[ind][2] == 1){
						ll i = c[ind][1];
						ans[i] = 'R';
					}
				}
			}	

			assert(!j);
		}

		return dp1[0] >= 0;
	};

	ll lo = 0, hi = inf1;
	ll best = -1;

	while(lo <= hi){
		ll mid = (lo+hi) >> 1;
		if(ok(mid,0)){
			best = mid;
			hi = mid-1;
		}
		else{
			lo = mid+1;
		}
	}

	cout << best << endl;
	if(best == -1) return;

	ok(best,1);
	// rep1(i,n) cout << ans[i];
	// cout << endl;

	rep1(i,m){
		if(b[i] == -1) conts;
		ll x = b[i];
		bool good = false;
		rep1(j,n){
			ll l = -1, r = -1;
			if(ans[j] == 'R'){
				l = a[j], r = a[j]+best;
			}
			else{
				l = a[j]-best, r = a[j];
			}

			if(l <= x and x <= r){
				good = true;
				break;
			}
		}

		if(!good){
			assert(0);
		}
	}
}

int main(){
	int t = 1;
	// cin >> t;

	rep1(i,t){
		solve(i);
	}

	return 0;
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 3
• Subtask 2: 0 / 6
• Subtask 3: 0 / 17
• Subtask 4: 0 / 27
• Subtask 5: 0 / 47