Submission #522402

#	Time	Username	Problem	Language	Result	Execution time	Memory
522402		LucaDantas	Alternating Current (BOI18_alternating)	C++17	0 / 100	3017 ms	2376 KiB

alternating

#include <bits/stdc++.h>
using namespace std;

constexpr int maxn = 1e5+10;

using pii = pair<int,int>;

vector<pair<pii, int>> wires;

bool mark[maxn][2];

int n;

void go(int l, int r, int c) { for(int i = l; i <= r; i++) mark[(i-1)%n+1][c] = 1; }

bool bom() {
	for(int i = 1; i <= n; i++)
		if(!mark[i][0] || !mark[i][1]) return 0;
	return 1;
}

int main() {
	int m; scanf("%d %d", &n, &m);
	for(int i = 0, a, b; i < m; i++) {
		scanf("%d %d", &a, &b);
		if(b < a) b += n;
		wires.push_back({{a, b}, i});
	}
	sort(wires.begin(), wires.end());

	vector<int> ans(m);
	int a = 1, b = 1, cor = 0;
	for(int i = 0; i < m; i++) {
		if(a > b) swap(a, b), cor ^= 1;
		a = max(a, wires[i].first.second + 1);
		go(wires[i].first.first, wires[i].first.second, cor);
		ans[wires[i].second] = cor;
	}

	if(!bom()) return puts("impossible"), 0;

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

Compilation message (stderr)

alternating.cpp: In function 'int main()':
alternating.cpp:23:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |  int m; scanf("%d %d", &n, &m);
      |         ~~~~~^~~~~~~~~~~~~~~~~
alternating.cpp:25:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |   scanf("%d %d", &a, &b);
      |   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 13
• Subtask 2: 0 / 20
• Subtask 3: 0 / 22
• Subtask 4: 0 / 19
• Subtask 5: 0 / 26