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Submission #120342

# Submission time Handle Problem Language Result Execution time Memory
120342 2019-06-24T08:33:23 Z tmwilliamlin168 Printed Circuit Board (CEOI12_circuit) C++14
100 / 100
 43 ms 4608 KB 
#include <bits/stdc++.h>
using namespace std;

#define ll long long

const int mxN=2e5;
int n, l, r;
ll x[mxN+1], y[mxN+1];
vector<int> v, s;
bool b[mxN];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	auto cp=[](int a, int b, int c) {
		return (y[c]-y[a])*(x[b]-x[a])-(y[b]-y[a])*(x[c]-x[a]);
	};
	cin >> n;
	for(int i=0; i<n; ++i) {
		cin >> x[i] >> y[i];
		if(!i||cp(n, l, i)>0||!cp(n, l, i)&&x[i]<x[l])
			l=i;
		if(!i||cp(n, r, i)<0||!cp(n, r, i)&&x[i]<x[r])
			r=i;
	}
	int ic=cp((l+n-1)%n, l, (l+1)%n)>0?1:n-1;
	for(; l^r; l=(l+ic)%n)
		v.push_back(l);
	v.push_back(r);
	s={0, 1};
	for(int i=2; i<v.size(); ++i) {
		auto updLeft=[&]() {
			while(cp(n, v[s.back()], v[i])>=0&&cp(v[i-1], v[i], v[s.back()])<=0)
				s.pop_back();
			for(int j=i, c=cp(n, v[s.back()], v[i])<0; cp(n, v[s.back()], v[i])>=0||!c; ++i) {
				if(i^j?cp(n, v[j], v[i])>=0&&cp(n, v[j], v[i+1])<0&&cp(v[i], v[i+1], v[j])>0:cp(n, v[i], v[i+1])<0&&cp(v[i-1], v[i], v[i+1])>0)
					++c;
				if(cp(n, v[j], v[i])<0&&cp(n, v[j], v[i+1])>=0&&cp(v[i], v[i+1], v[j])<0)
					--c;
			}
		};
		auto escapeRight=[&]() {
			while(cp(n, v[s.back()], v[i])<=0)
				++i;
			s.pop_back();
			updLeft();
		};
		if(cp(n, v[i-1], v[i])<0) {
			if(cp(n, v[i-2], v[i-1])>0&&cp(v[i-2], v[i-1], v[i])<0)
				escapeRight();
		} else if(cp(n, v[i-1], v[i])>0) {
			if(cp(n, v[i-2], v[i-1])<0&&cp(v[i-2], v[i-1], v[i])>0)
				while(cp(n, v[s.back()], v[i])>=0)
					++i;
			else
				updLeft();
		}
		else {
			if((cp(n, v[i-2], v[i-1])<0)==(cp(v[i-2], v[i-1], v[i])<0))
				s.pop_back();
			else if(cp(n, v[i-2], v[i-1])<0)
				while(cp(n, v[s.back()], v[i])>=0)
					++i;
			else
				escapeRight();
		}
		s.push_back(i);
	}
	cout << s.size() << "\n";
	for(int a : s)
		b[v[a]]=1;
	for(int i=0; i<n; ++i)
		if(b[i])
			cout << i+1 << " ";
}

Compilation message

circuit.cpp: In function 'int main()':
circuit.cpp:22:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, l, i)>0||!cp(n, l, i)&&x[i]<x[l])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:24:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, r, i)<0||!cp(n, r, i)&&x[i]<x[r])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:32:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=2; i<v.size(); ++i) {
               ~^~~~~~~~~

Subtask #1
100.0 / 100.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 384 KB Output is correct
2 Correct 2 ms 384 KB Output is correct
3 Correct 3 ms 512 KB Output is correct
4 Correct 3 ms 512 KB Output is correct
5 Correct 4 ms 640 KB Output is correct
6 Correct 4 ms 640 KB Output is correct
7 Correct 6 ms 768 KB Output is correct
8 Correct 3 ms 512 KB Output is correct
9 Correct 4 ms 640 KB Output is correct
10 Correct 4 ms 640 KB Output is correct
11 Correct 4 ms 640 KB Output is correct
12 Correct 6 ms 896 KB Output is correct
13 Correct 9 ms 1024 KB Output is correct
14 Correct 9 ms 1152 KB Output is correct
15 Correct 11 ms 1536 KB Output is correct
16 Correct 20 ms 2560 KB Output is correct
17 Correct 22 ms 2296 KB Output is correct
18 Correct 41 ms 4604 KB Output is correct
19 Correct 42 ms 4608 KB Output is correct
20 Correct 43 ms 4596 KB Output is correct