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답안 #527640

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
527640 2022-02-17T21:14:09 Z LucaDantas Alternating Current (BOI18_alternating) C++17
19 / 100
 40 ms 5636 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];
		pref[i+n] = pref[i];
		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(min(l, r) < ini_mx, r)) {
			brabos.push_back(wr[i]);
			aberto = id;
			fim = r;
			virou |= min(l, r) < 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();
	}

	sort(brabos.begin(), brabos.end(), [](const Wire& a, const Wire& b) { return a.l < b.l; });

	for(int i = 0; i < brabos.size(); i++) {
		auto nxt = [&](int x) { return (x+1) % brabos.size(); };
		auto eu = brabos[i], prox = brabos[nxt(i)];
		int l = prox.l, r = eu.r;
		
		if(r < l) r += n;

		bool tem = 1;
		for(int j = l; j <= r; j++)
			tem &= pref[j] >= 3;

		auto no_intersection = [](Wire a, Wire b) {
			if(a.r < a.l) a.r += n;
			if(b.r < b.l) b.r += n;

			if(a.r < b.l) return 1;
			return 0;
		};
		if(tem || no_intersection(eu, prox)) {
			// printf("BOM %d | %d %d\n", i, l, r);

			bool opa = 1;
			ans[ brabos[i].id ] = opa;

			for(int j = nxt(i); j != i; j = nxt(j)) {
				ans[ brabos[j].id ] = opa;
				opa ^= 1;
			}

			for(int i = 0; i < m; i++)
				if(pai[i] != -1) ans[i] = 1^ans[pai[i]];

			print();
		}
	}

	puts("impossible");
}

Compilation message

alternating.cpp: In function 'int main()':
alternating.cpp:85:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Wire>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |   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: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;
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 13.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1396 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 1396 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 1396 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 28 ms 4776 KB Output is correct
2 Correct 2 ms 2200 KB Output is correct
3 Correct 11 ms 1760 KB Output is correct
4 Correct 15 ms 3620 KB Output is correct
5 Correct 35 ms 5388 KB Output is correct
6 Correct 23 ms 3012 KB Output is correct
7 Correct 34 ms 4964 KB Output is correct
8 Correct 2 ms 2252 KB Output is correct
9 Correct 2 ms 2228 KB Output is correct
10 Correct 38 ms 5636 KB Output is correct
11 Correct 27 ms 4672 KB Output is correct
12 Correct 32 ms 4696 KB Output is correct
13 Correct 1 ms 972 KB Output is correct
14 Correct 1 ms 1068 KB Output is correct
15 Correct 36 ms 5060 KB Output is correct
16 Correct 9 ms 2232 KB Output is correct
17 Correct 37 ms 5056 KB Output is correct
18 Correct 33 ms 4036 KB Output is correct
19 Correct 2 ms 716 KB Output is correct
20 Correct 40 ms 5284 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 1396 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 -