Submission #187531

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
187531	2020-01-13T02:39:08 Z	dndhk	Watching (JOI13_watching)	C++14	50 / 100	1000 ms	18680 KB

watching

#include <bits/stdc++.h>

#define pb push_back

using namespace std;

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

const int MAX_N = 2000;
const ll INFLL = 10000;
int N, P, Q;
vector<ll> v;

int dp[MAX_N+1][MAX_N+1];

int lb(ll x){
	//cout<<"?"<<x<<" ";
	int s = 1, e = v.size()-1, m;
	while(s<e){
		m = (s+e)/2+1;
		//cout<<m<<" "<<v[m]<<endl;

		if(v[m]<=x)	s = m;
		else	e = m-1;
	}
	//cout<<s<<endl;
	return s;
}

deque<pii> dq[2][MAX_N+1];

void add(int idx, int x, int y, int z){
	while(!dq[idx][x].empty() && dq[idx][x].back().first>=z){
		dq[idx][x].pop_back();
	}
	dq[idx][x].push_back({z, y});
}

bool chk(ll x){
	for(int i=0; i<=N; i++){
		for(int j=0; j<=N; j++)	dp[i][j] = INFLL;
		while(!dq[0][i].empty())	dq[0][i].pop_back();
		while(!dq[1][i].empty())	dq[1][i].pop_back();
	}
	dp[0][0] = 0LL;
	//cout<<x<<endl;
	for(int i=0; i<=N; i++){
		for(int j=N; j>=0; j--){
			while(!dq[0][j].empty() && dq[0][j].front().second<i)	dq[0][j].pop_front();
			while(!dq[1][j].empty() && dq[1][j].front().second<i)	dq[1][j].pop_front();
			if(dq[0][j].empty()){
				if(!dq[1][j].empty())	dp[i][j] = dq[1][j].front().first;
			}else{
				if(dq[1][j].empty())	dp[i][j] = dq[0][j].front().first;
				else{
					dp[i][j] = min(dq[0][j].front().first, dq[1][j].front().first);
				}
			}
			//cout<<i<<" "<<j<<" "<<dp[i][j]<<endl;
			if(dp[i][j]==INFLL || i==N)	continue;
			int k = dp[i][j];
			int r1 = lb(v[i+1]+x-1LL), r2 = lb(v[i+1]+2LL*x-1LL);
			add(0, j+1, r1, k);
			add(1, j, r2, k+1);
		}
	}
	for(int i=0; i<=P; i++){
		if(dp[N][i]<=Q)	return true;
	}
	return false;
}

int main(){
	scanf("%d%d%d", &N, &P, &Q);	
	v.pb(0);
	for(int i=1; i<=N; i++){
		ll x; scanf("%lld", &x);
		v.pb(x);
	}
	sort(v.begin(), v.end());
	v.erase(unique(v.begin(), v.end()), v.end());
	N = v.size()-1;
	ll s = 1LL, e = 1000000000LL, m;
	while(s<e){
		m = (s+e)/2LL;
		if(chk(m)){
			e = m;
		}else{
			s = m+1;
		}
	}
	printf("%lld", s);
}

Compilation message

watching.cpp: In function 'int main()':
watching.cpp:76:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &N, &P, &Q); 
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~
watching.cpp:79:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   ll x; scanf("%lld", &x);
         ~~~~~^~~~~~~~~~~~

Subtask #1

50.0 / 50.0

#	Verdict	Execution time	Memory	Grader output
1	Correct	13 ms	3576 KB	Output is correct
2	Correct	5 ms	3064 KB	Output is correct
3	Correct	4 ms	3064 KB	Output is correct
4	Correct	13 ms	3624 KB	Output is correct
5	Correct	15 ms	3452 KB	Output is correct
6	Correct	17 ms	3320 KB	Output is correct
7	Correct	14 ms	3448 KB	Output is correct
8	Correct	13 ms	3420 KB	Output is correct
9	Correct	15 ms	3448 KB	Output is correct
10	Correct	15 ms	3448 KB	Output is correct
11	Correct	15 ms	3576 KB	Output is correct
12	Correct	17 ms	3576 KB	Output is correct
13	Correct	13 ms	3448 KB	Output is correct
14	Correct	12 ms	3448 KB	Output is correct
15	Correct	14 ms	3448 KB	Output is correct

Subtask #2

0 / 50.0

#	Verdict	Execution time	Memory	Grader output
1	Execution timed out	1077 ms	18680 KB	Time limit exceeded
2	Halted	0 ms	0 KB	-