oj.uz

Submission #527628

# Submission time Handle Problem Language Result Execution time Memory
527628 2022-02-17T20:55:35 Z LucaDantas Alternating Current (BOI18_alternating) C++17
19 / 100
 46 ms 4424 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();
	}

	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;

		if(tem || l == r % n + 1) {
			// 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:94:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<Wire>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |  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

# Verdict Execution time Memory Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1484 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

# Verdict Execution time Memory Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1484 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

# Verdict Execution time Memory Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1484 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

# Verdict Execution time Memory Grader output
1 Correct 25 ms 3884 KB Output is correct
2 Correct 1 ms 2252 KB Output is correct
3 Correct 8 ms 1160 KB Output is correct
4 Correct 16 ms 3080 KB Output is correct
5 Correct 46 ms 4204 KB Output is correct
6 Correct 18 ms 1976 KB Output is correct
7 Correct 33 ms 3988 KB Output is correct
8 Correct 2 ms 2252 KB Output is correct
9 Correct 2 ms 2124 KB Output is correct
10 Correct 39 ms 4424 KB Output is correct
11 Correct 27 ms 3876 KB Output is correct
12 Correct 32 ms 3660 KB Output is correct
13 Correct 1 ms 1048 KB Output is correct
14 Correct 1 ms 972 KB Output is correct
15 Correct 46 ms 3920 KB Output is correct
16 Correct 9 ms 1628 KB Output is correct
17 Correct 36 ms 3832 KB Output is correct
18 Correct 34 ms 3268 KB Output is correct
19 Correct 2 ms 716 KB Output is correct
20 Correct 40 ms 4196 KB Output is correct

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 1356 KB Output is correct
2 Correct 1 ms 1484 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 -