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Submission #120347

# Submission time Handle Problem Language Result Execution time Memory
120347 2019-06-24T08:39:36 Z tmwilliamlin168 Printed Circuit Board (CEOI12_circuit) C++14
100 / 100
 46 ms 6064 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;
			}
		};
		auto el=[&]() {
			while(cp(n, v[s.back()], v[i])>=0)
				++i;
		};
		auto er=[&]() {
			while(cp(n, v[s.back()], v[i])<=0)
				++i;
			s.pop_back();
			ul();
		};
		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)
				er();
		} 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)
				el();
			else
				ul();
		} 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)
				el();
			else
				er();
		}
		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 640 KB Output is correct
7 Correct 7 ms 1024 KB Output is correct
8 Correct 4 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 5 ms 640 KB Output is correct
12 Correct 6 ms 1024 KB Output is correct
13 Correct 9 ms 1280 KB Output is correct
14 Correct 9 ms 1536 KB Output is correct
15 Correct 11 ms 2048 KB Output is correct
16 Correct 21 ms 3708 KB Output is correct
17 Correct 25 ms 3584 KB Output is correct
18 Correct 43 ms 6004 KB Output is correct
19 Correct 41 ms 6064 KB Output is correct
20 Correct 46 ms 6004 KB Output is correct