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Submission #120373

# Submission time Handle Problem Language Result Execution time Memory
120373 2019-06-24T09:23:43 Z tmwilliamlin168 Printed Circuit Board (CEOI12_circuit) C++14
100 / 100
 45 ms 4724 KB 
#include <bits/stdc++.h>
using namespace std;

const int mxN=2e5;
int n, l, r;
long long 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 ul=[&]() {
			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;
			}
		};
		if(!cp(n, v[i-1], v[i])&&(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-1], v[i])<=0&&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;
			s.pop_back();
			ul();
		} else if(cp(n, v[i-1], v[i])>0&&(cp(n, v[i-2], v[i-1])>=0||cp(v[i-2], v[i-1], v[i])<0))
			ul();
		else if(cp(n, v[i-1], v[i])>=0)
			while(cp(n, v[s.back()], v[i])>=0)
				++i;
		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:20:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, l, i)>0||!cp(n, l, i)&&x[i]<x[l])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:22:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, r, i)<0||!cp(n, r, i)&&x[i]<x[r])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:30:16: 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 5 ms 512 KB Output is correct
7 Correct 12 ms 896 KB Output is correct
8 Correct 3 ms 512 KB Output is correct
9 Correct 4 ms 640 KB Output is correct
10 Correct 5 ms 640 KB Output is correct
11 Correct 5 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 1280 KB Output is correct
15 Correct 11 ms 1536 KB Output is correct
16 Correct 27 ms 2560 KB Output is correct
17 Correct 23 ms 2296 KB Output is correct
18 Correct 41 ms 4724 KB Output is correct
19 Correct 41 ms 4580 KB Output is correct
20 Correct 45 ms 4724 KB Output is correct