Submission #58272

#	Time	Username	Problem	Language	Result	Execution time	Memory
58272		memikakizaki	Teleporters (IOI08_teleporters)	C++14	100 / 100	855 ms	54844 KiB

teleporters

#include <bits/stdc++.h>
#define long long long
using namespace std;
const int N = 1e6+3, INF = 1e9;

int n, m, lf[N], rg[N], rev[2*N], nxt[2*N];
int cycles[N], idx;
bitset<N<<1> mark;
long ans;
int main() {
	scanf("%d %d", &n, &m);
	for(int i = 0; i < n; i++) {
		scanf("%d %d", &lf[i], &rg[i]);
		nxt[i<<1] = lf[i];
		nxt[i<<1|1] = rg[i];
	}
	sort(nxt, nxt+2*n+1); // use nxt as val array
	for(int i = 0; i <= n << 1; i++) rev[nxt[i]] = i;
	for(int i = 0; i < n; i++) {
		nxt[rev[lf[i]]-1] = rev[rg[i]];
		nxt[rev[rg[i]]-1] = rev[lf[i]];
	}
	nxt[2*n] = INF;
	for(int i = 0; i <= n << 1; i++) if(!mark[i]) {
		int curr = i, sz = 0;
		bool cycle = false;
		while(curr != INF) {
			if(mark[curr]) {
				cycle = true;
				break;
			}
			++sz;
			mark[curr] = true;
			curr = nxt[curr];
		}
		if(cycle) cycles[idx++] = sz;
		else ans = sz-1;
	}
	sort(cycles, cycles+idx, greater<int>());
	for(int i = 0; i < min(idx, m); i++) ans += cycles[i] + 2;
	if(m > idx) {
		m -= idx;
		ans += ((m - (m & 1)) << 1) + (m & 1);
	}
	printf("%lld", ans);
}

Compilation message (stderr)

teleporters.cpp: In function 'int main()':
teleporters.cpp:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~~
teleporters.cpp:13:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &lf[i], &rg[i]);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
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