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답안 #527623

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
527623 2022-02-17T20:36:25 Z LucaDantas Alternating Current (BOI18_alternating) C++17
19 / 100
 48 ms 4124 KB 
#include <bits/stdc++.h>
using namespace std;

constexpr int maxn = 3e5+10;

int pref[maxn];
int mx = 0, ini_mx = 0, n, m;

struct Wire {
	int l, r, id;
	int sz() const { return r >= l ? r - l + 1 : r + (n - l + 1); }
	bool operator<(const Wire& o) const {
		if(l == o.l) return this->sz() > o.sz();
		if((l >= ini_mx) == (o.l >= ini_mx)) return l < o.l; // retorno o que tem o menor l já que eles são da mesma metade
		return l > o.l; // já que eles são de metades diferentes eu retorno o que tiver na metade maior
	}
} wr[maxn];

int pai[maxn];

int main() {
	scanf("%d %d", &n, &m);
	for(int i = 0; i < m; i++) {
		scanf("%d %d", &wr[i].l, &wr[i].r); wr[i].id = i;
		if(wr[i].l <= wr[i].r) {
			pref[wr[i].l]++;
			pref[wr[i].r+1]--;
		} else {
			pref[wr[i].l]++;
			pref[1]++;
			pref[wr[i].r+1]--;
		}
		
		if(wr[i].sz() > mx) {
			mx = wr[i].sz();
			ini_mx = wr[i].l;
		}
	}

	for(int i = 1; i <= n; i++) {
		pref[i] += pref[i-1];
		if(pref[i] < 2) return puts("impossible"), 0;
	}

	sort(wr, wr+m);

	bool virou = 0;
	int fim = 0, aberto = -1;

	vector<Wire> brabos;

	memset(pai, -1, sizeof pai);
	for(int i = 0; i < m; i++) {
		auto [l, r, id] = wr[i];
		if(make_pair(virou, fim) < make_pair(r < l || l < ini_mx, r)) {
			brabos.push_back(wr[i]);
			aberto = id;
			fim = r;
			virou |= r < l || l < ini_mx;
		} else pai[id] = aberto;
	}

	/* puts("BRABOS: ");
	printf("Size: %ld\n", brabos.size());
	for(Wire x : brabos)
		printf("(%d %d %d) ", x.l, x.r, x.id);
	puts(""); */

	vector<int> ans(m);

	auto print = [&]() {
		for(int i = 0; i < m; i++)
			printf("%d", ans[i]);
		puts("");
		exit(0);
	};

	if(brabos[0].sz() == n) {
		ans[brabos[0].id] = 1;
		print();
	}

	if(brabos.size() % 2 == 0) {
		for(int i = 0; i < brabos.size(); i++)
			ans[brabos[i].id] = i&1;
		
		for(int i = 0; i < m; i++)
			if(pai[i] != -1) ans[i] = 1^ans[pai[i]];

		print();
	}

	brabos.push_back(brabos.front());

	int r_a = -1;
	for(int i = 0; i < brabos.size(); i++) {
		auto [l, r, id] = brabos[i];
		if(r_a != -1) {
			bool tem = pref[r_a] >= 3;
			static int cnt = 0;
			for(int j = l; j != (r_a-1)%n + 1; j = (j%n)+1)
				tem &= pref[j] >= 3;
 
			if(l == ((r_a)%n+1) || tem) {
				brabos.pop_back();
				if(i == brabos.size()) i = 0;
 
				auto nxt = [&](int x) { return x%brabos.size()+1; };
 
				ans[brabos[i].id] = 1;
				for(int k = i+1, opa = 0; k != i; k = nxt(k), opa ^= 1)
					ans[brabos[k].id] = opa;
		
				for(int i = 0; i < m; i++)
					if(pai[i] != -1) ans[i] = 1^ans[pai[i]];

				print();
			}
 
		}
		r_a = r;
	}
	puts("impossible");
}

Compilation message

alternating.cpp: In function 'int main()':
alternating.cpp:84:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Wire>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |   for(int i = 0; i < brabos.size(); i++)
      |                  ~~^~~~~~~~~~~~~~~
alternating.cpp:96:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Wire>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   96 |  for(int i = 0; i < brabos.size(); i++) {
      |                 ~~^~~~~~~~~~~~~~~
alternating.cpp:106:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Wire>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |     if(i == brabos.size()) i = 0;
      |        ~~^~~~~~~~~~~~~~~~
alternating.cpp:100:15: warning: unused variable 'cnt' [-Wunused-variable]
  100 |    static int cnt = 0;
      |               ^~~
alternating.cpp:22:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |  scanf("%d %d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~~
alternating.cpp:24:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |   scanf("%d %d", &wr[i].l, &wr[i].r); wr[i].id = i;
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
alternating.cpp: At global scope:
alternating.cpp:100:15: warning: 'cnt' defined but not used [-Wunused-variable]
  100 |    static int cnt = 0;
      |               ^~~

Subtask #1
0 / 13.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1356 KB Output is correct
3 Incorrect 1 ms 1356 KB no wires in direction 1 between segments 14 and 15
4 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1356 KB Output is correct
3 Incorrect 1 ms 1356 KB no wires in direction 1 between segments 14 and 15
4 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1356 KB Output is correct
3 Incorrect 1 ms 1356 KB no wires in direction 1 between segments 14 and 15
4 Halted 0 ms 0 KB -

Subtask #4
19.0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 26 ms 3520 KB Output is correct
2 Correct 2 ms 1868 KB Output is correct
3 Correct 11 ms 1180 KB Output is correct
4 Correct 15 ms 2704 KB Output is correct
5 Correct 43 ms 3836 KB Output is correct
6 Correct 19 ms 1748 KB Output is correct
7 Correct 33 ms 3584 KB Output is correct
8 Correct 2 ms 1868 KB Output is correct
9 Correct 1 ms 1740 KB Output is correct
10 Correct 37 ms 4124 KB Output is correct
11 Correct 27 ms 3388 KB Output is correct
12 Correct 31 ms 3276 KB Output is correct
13 Correct 1 ms 588 KB Output is correct
14 Correct 1 ms 588 KB Output is correct
15 Correct 35 ms 3528 KB Output is correct
16 Correct 9 ms 1276 KB Output is correct
17 Correct 34 ms 3432 KB Output is correct
18 Correct 34 ms 3148 KB Output is correct
19 Correct 2 ms 716 KB Output is correct
20 Correct 48 ms 3952 KB Output is correct

Subtask #5
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1356 KB Output is correct
3 Incorrect 1 ms 1356 KB no wires in direction 1 between segments 14 and 15
4 Halted 0 ms 0 KB -