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Submission #120336

# Submission time Handle Problem Language Result Execution time Memory
120336 2019-06-24T08:22:30 Z tmwilliamlin168 Printed Circuit Board (CEOI12_circuit) C++14
100 / 100
 44 ms 4724 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];

ll cp(int a, int b, int c) {
	return (y[c]-y[a])*(x[b]-x[a])-(y[b]-y[a])*(x[c]-x[a]);
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	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 escapeRightLeft=[&]() {
			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])<0) {
			if(cp(n, v[i-2], v[i-1])>0&&cp(v[i-2], v[i-1], v[i])<0) {
				//while hidden
				while(cp(n, v[s.back()], v[i])<=0)
					++i;
				s.pop_back();
				while(cp(n, v[s.back()], v[i])>=0&&cp(v[i-1], v[i], v[s.back()])<0)
					s.pop_back();
				escapeRightLeft();
			}
		}
		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 {
				while(cp(n, v[s.back()], v[i])>=0&&cp(v[i-1], v[i], v[s.back()])<=0)
					s.pop_back();
				escapeRightLeft();
			}
		}
		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 {
				while(cp(n, v[s.back()], v[i])<=0)
					++i;
				s.pop_back();
				while(cp(n, v[s.back()], v[i])>=0&&cp(v[i-1], v[i], v[s.back()])<0)
					s.pop_back();
				escapeRightLeft();
			}
		}
		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:23:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, l, i)>0||!cp(n, l, i)&&x[i]<x[l])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:25:37: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(!i||cp(n, r, i)<0||!cp(n, r, i)&&x[i]<x[r])
                         ~~~~~~~~~~~~^~~~~~~~~~~
circuit.cpp:33:16: 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 2 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 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 4 ms 768 KB Output is correct
11 Correct 4 ms 640 KB Output is correct
12 Correct 5 ms 896 KB Output is correct
13 Correct 8 ms 1152 KB Output is correct
14 Correct 9 ms 1196 KB Output is correct
15 Correct 11 ms 1536 KB Output is correct
16 Correct 21 ms 2708 KB Output is correct
17 Correct 22 ms 2304 KB Output is correct
18 Correct 39 ms 4724 KB Output is correct
19 Correct 40 ms 4696 KB Output is correct
20 Correct 44 ms 4568 KB Output is correct