Submission #772546

#	Time	Username	Problem	Language	Result	Execution time	Memory
772546		kingfran1907	Teleporters (IOI08_teleporters)	C++14	100 / 100	879 ms	64052 KiB

teleporters

#include <bits/stdc++.h>

using namespace std;
typedef long long llint;

const int maxn = 25e5+10;
const int inf = 0x3f3f3f3f;

int n, m;
int l[maxn], r[maxn];
vector< int > v;
vector< pair<int, int> > vs;
int nex[maxn];
bool bio[maxn];
priority_queue< int > cycles;

int main() {
	scanf("%d%d", &n, &m);
	for (int i = 0; i < n; i++)
		scanf("%d%d", l+i, r+i);
	l[n] = -1;
	r[n] = inf;
	n++;
	
	for (int i = 0; i < n; i++) {
		v.push_back(l[i]);
		v.push_back(r[i]);
	}
	sort(v.begin(), v.end());
	for (int i = 0; i < n; i++) {
		l[i] = lower_bound(v.begin(), v.end(), l[i]) - v.begin();
		r[i] = lower_bound(v.begin(), v.end(), r[i]) - v.begin();
		vs.push_back({l[i], i});
		vs.push_back({r[i], i});
	}
	sort(vs.begin(), vs.end());
	
	for (int i = 0; i < v.size() - 1; i++) {
		int ind = vs[i + 1].second;
		int rs = l[ind] + r[ind] - vs[i + 1].first;
		nex[i] = rs;
	}
	
	int sol = 0;
	for (int i = 0; i < v.size() - 1; i++) {
		//printf("trying: %d\n", i);
		if (bio[i]) continue;
		int cnt = 0;
		int ptr = i;
		
		//printf("cycle: ");
		while (!bio[ptr]) {
			//printf("%d ", ptr);
			bio[ptr] = true;
			ptr = nex[ptr];
			cnt++;
		}
		//printf("\n");
		if (i > 0) cycles.push(cnt);
		else sol = cnt - 1;
	}
	
	while (m && !cycles.empty()) { 
		//printf("debug: %d\n", cycles.top());
		sol += cycles.top() + 2;
		cycles.pop();
		m--;
	}
	//printf("%d - %d\n", m, cycles.size());
	m = m -= min(m, (int)cycles.size());
	sol += 2 * (m - m % 2) + m % 2;
	printf("%d\n", sol);
	return 0;
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:38:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |  for (int i = 0; i < v.size() - 1; i++) {
      |                  ~~^~~~~~~~~~~~~~
teleporters.cpp:45:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |  for (int i = 0; i < v.size() - 1; i++) {
      |                  ~~^~~~~~~~~~~~~~
teleporters.cpp:70:4: warning: operation on 'm' may be undefined [-Wsequence-point]
   70 |  m = m -= min(m, (int)cycles.size());
      |  ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
teleporters.cpp:18:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |  scanf("%d%d", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~
teleporters.cpp:20:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |   scanf("%d%d", l+i, r+i);
      |   ~~~~~^~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5
• Subtask 6: 5 / 5
• Subtask 7: 5 / 5
• Subtask 8: 5 / 5
• Subtask 9: 5 / 5
• Subtask 10: 5 / 5
• Subtask 11: 5 / 5
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• Subtask 14: 5 / 5
• Subtask 15: 5 / 5
• Subtask 16: 5 / 5
• Subtask 17: 5 / 5
• Subtask 18: 5 / 5
• Subtask 19: 5 / 5
• Subtask 20: 5 / 5