Submission #71662

#	Time	Username	Problem	Language	Result	Execution time	Memory
71662		Navick	Sorting (IOI15_sorting)	C++17	36 / 100	4 ms	768 KiB

sorting

#include <bits/stdc++.h>
#include "sorting.h"

#define F first
#define S second
#define pii pair<int, int>
#define pb push_back

typedef long long ll;

using namespace std;

const int maxN = 2e5 + 10, maxM = 3 * maxN;

int x[maxM], y[maxM];
int n, q[maxN], tmp[maxN], p[maxN];
bool mark[maxN];
vector <int> a1 ,a2;

int check(int m, bool f = 0)
{
	for (int i=0; i<m; i++)
	{
		int a = p[x[i]], b = p[y[i]];
		p[x[i]] = b, p[y[i]] = a;
	}

	memset(mark, 0, sizeof mark);
	int ted = 0;

	vector <pii > swaps;

	for (int i=0; i<n; i++)
	{
		if(mark[i]) continue ;
		vector <int> vc;
		ted ++;
		int curr = i;
		while(!mark[curr])
		{
			mark[curr] = true;
			if(!mark[p[curr]]) swaps.pb({curr, p[curr]});
			curr = p[curr];
		}
	}

	if(ted < n - m) return 0;
	else if(!f) return 1;

	for (int i=0; i<n; i++) p[i] = tmp[i], q[p[i]] = i;
	
	for (int i=0; i<m; i++)
	{
		int a = p[x[i]], b = p[y[i]];
		p[x[i]] = b, p[y[i]] = a;
		q[b] = x[i], q[a] = y[i];

		if(i >= swaps.size()) continue ;

		int v1 = swaps[i].F, v2 = swaps[i].S;

		int xi = q[v1], yi = q[v2];
		a = p[xi], b = p[yi];
		p[xi] = b, p[yi] = a;
		q[b] = xi, q[a] = yi;

		a1.pb(xi); a2.pb(yi);

	}

	return 1;

}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	n = N;
	int lo = -1, hi = M;
	
	for (int i=0; i<M; i++) x[i] = X[i], y[i] = Y[i];
	
	for (int i=0; i<n; i++) tmp[i] = S[i];

	while(hi - lo > 1)
	{
		for (int i=0; i<n; i++) p[i] = S[i];
		int mid = (lo + hi)/2;
		if(check(mid)) hi = mid;
		else lo = mid;
	}
	
	for (int i=0; i<n; i++) p[i] = S[i];
	check(hi, 1);
	for (int i=0; i<hi; i++) P[i] = a1[i], Q[i] = a2[i];
	return hi;
}

Compilation message (stderr)

sorting.cpp: In function 'int check(int, bool)':
sorting.cpp:58:8: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if(i >= swaps.size()) continue ;
      ~~^~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 16 / 16
• Subtask 4: 0 / 18
• Subtask 5: 0 / 20
• Subtask 6: 0 / 26