Submission #187534

#	Time	Username	Problem	Language	Result	Execution time	Memory
187534		dndhk	Watching (JOI13_watching)	C++14	50 / 100	1031 ms	16348 KiB

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 = 2002;
const ll INFLL = 10000;
int N, P, Q;
vector<ll> v;

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

list<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;
	int r1=0, r2=0;
	for(int i=0; i<=N; i++){
		while(r1<v.size()-1 && v[r1+1]<=v[i+1]+x-1LL){
			r1++;
		}
		while(r2<v.size()-1 && v[r2+1]<=v[i+1]+2LL*x-1LL){
			r2++;
		}
		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);
				}
			}
			if(dp[i][j]==INFLL || i==N)	continue;
			int k = dp[i][j];
			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());
	sort(v.begin(), 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 (stderr)

watching.cpp: In function 'bool chk(ll)':
watching.cpp:37:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(r1<v.size()-1 && v[r1+1]<=v[i+1]+x-1LL){
         ~~^~~~~~~~~~~
watching.cpp:40:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   while(r2<v.size()-1 && v[r2+1]<=v[i+1]+2LL*x-1LL){
         ~~^~~~~~~~~~~
watching.cpp: In function 'int main()':
watching.cpp:67:7: 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:70:14: 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 / 50
• Subtask 2: 0 / 50