Submission #135246

#	Time	Username	Problem	Language	Result	Execution time	Memory
135246		JustasZ	Sorting (IOI15_sorting)	C++14	20 / 100	4 ms	760 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) (int)a.size()
#define x first
#define y second
#define debug(...) cout << "[" << #__VA_ARGS__ << ": " << __VA_ARGS__ << "]\n"
#define rd() abs((int)rng())
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int>pii;
const int maxn = 2e5 + 100;
const int mod = 1e9 + 7;
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
int findSwapPairs(int n, int arr[], int m, int X[], int Y[], int P[], int Q[])
{
	auto chk = [&](int val, bool f = false) -> bool
	{
		vector<int>finalpos(n, 0), cur(n, 0);
		for(int i = 0; i < n; i++)
			cur[i] = i;
		for(int i = 0; i < val; i++)
			swap(cur[X[i]], cur[Y[i]]);
		for(int i = 0; i < n; i++)
			finalpos[cur[i]] = i;

		vector<int>where(n), v(n);
		for(int i = 0; i < n; i++)
		{
			v[i] = arr[i];
			where[v[i]] = i;
		}

		int sw = 0;
		for(int i = 0; i < n; i++)
		{
			if(finalpos[i] != v[i])
			{
				if(sw >= val)
					return false;
				int pos = where[finalpos[i]];
				swap(v[pos], v[i]);
				P[sw] = pos, Q[sw] = i;
				swap(where[v[i]], where[v[pos]]);
				swap(finalpos[X[sw]], finalpos[Y[sw]]);
				swap(v[X[sw]], v[Y[sw]]);
				swap(where[v[X[sw]]], where[v[Y[sw]]]);
				++sw;
				--i;
			}
		}

		while(sw < m)
		{
			P[sw] = Q[sw] = 0;
			++sw;
		}
		return true;
	};
	int l = 0, r = m;
	while(l < r)
	{
		int mid = (l + r) / 2;
		if(chk(mid))
			r = mid;
		else
			l = mid + 1; 
	}
	chk(l);
	for(int i = 0; i < l; i++)
	{
		swap(arr[P[i]], arr[Q[i]]);
		swap(arr[X[i]], arr[Y[i]]);
	}
	assert(is_sorted(arr, arr + n));
	return l;
}

Compilation message (stderr)

sorting.cpp: In lambda function:
sorting.cpp:19:35: warning: unused parameter 'f' [-Wunused-parameter]
  auto chk = [&](int val, bool f = false) -> bool
                                   ^~~~~

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