Submission #712091

#	Time	Username	Problem	Language	Result	Execution time	Memory
712091		Pherokung	Lightning Rod (NOI18_lightningrod)	C++14	66 / 100	1992 ms	262144 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define MAXN 10000005
#define F first
#define S second
int n,x[MAXN],y[MAXN],l[MAXN],r[MAXN],ans=0;
vector<pair<int,int> > v;
deque<int> dq;
bool oper(pair<int,int> i,pair<int,int> j){
	return i.F > j.F;
}

int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&x[i],&y[i]);
		v.push_back({y[i],i});
	}
	
	for(int i=1;i<=n;i++){
		while(!dq.empty()){
			int p = dq.front();
			if(y[i] - x[i] >= y[p] - x[p]){
				r[p] = i;
				dq.pop_front();
			}
			else break;
		}
		dq.push_front(i);
	}
	while(!dq.empty()){
		r[dq.front()] = n+1;
		dq.pop_front();
	}
	
	for(int i=n;i>=1;i--){
		while(!dq.empty()){
			int p = dq.front();
			if(y[i] + x[i] >= y[p] + x[p]){
				l[p] = i;
				dq.pop_front();
			}
			else break;
		}
		dq.push_front(i);
	}
	while(!dq.empty()){
		l[dq.front()] = 0;
		dq.pop_front();
	}
	
	memset(x,0,sizeof x);
	sort(v.begin(),v.end(),oper);
	for(auto tw : v){
		int i = tw.S;
		if(!x[i] && !x[l[i]] && !x[r[i]]){
			ans++;
		}
		x[i] = 1;
	}
	
	printf("%d",ans);
}

Compilation message (stderr)

lightningrod.cpp: In function 'int main()':
lightningrod.cpp:14:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   14 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
lightningrod.cpp:16:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   16 |   scanf("%d%d",&x[i],&y[i]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 21 / 21
• Subtask 5: 26 / 26
• Subtask 6: 0 / 10
• Subtask 7: 0 / 20