Submission #88731

#	Time	Username	Problem	Language	Result	Execution time	Memory
88731		qkxwsm	Sorting (IOI15_sorting)	C++14	0 / 100	3 ms	512 KiB

sorting

#include "sorting.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

random_device(rd);
mt19937 rng(rd());
const long long FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();

struct custom_hash
{
	template<class T>
	unsigned long long operator()(T v) const
	{
		unsigned long long x = v;
		x += FIXED_RANDOM; x += 11400714819323198485ull;
		x = (x ^ (x >> 30)) * 13787848793156543929ull;
		x = (x ^ (x >> 27)) * 10723151780598845931ull;
		return x ^ (x >> 31);
	}
};

template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<class T, class U> using hash_table = gp_hash_table<T, U, custom_hash>;

template<class T>
void ckmin(T &a, T b)
{
	a = min(a, b);
}
template<class T>
void ckmax(T &a, T b)
{
	a = max(a, b);
}
long long expo(long long a, long long e, long long mod)
{
	return ((e == 0) ? 1 : ((expo(a * a % mod, e >> 1, mod)) * ((e & 1) ? a : 1) % mod));
}
template<class T, class U>
T nmod(T &x, U mod)
{
	if (x >= mod) x -= mod;
}
template<class T>
T gcd(T a, T b)
{
	return (b ? gcd(b, a % b) : a);
}
template<class T>
T randomize(T mod)
{
	return (uniform_int_distribution<T>(0, mod - 1))(rng);
}

#define y0 ___y0
#define y1 ___y1
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define PF push_front
#define fi first
#define se second
#define DBG(x) cerr << #x << " = " << x << endl;
#define SZ(x) ((int) (x.size()))
#define FOR(i, a, b) for (auto i = (a); i < (b); i++)
#define FORD(i, a, b) for (auto i = (a) - 1; i >= (b); i--)
#define ALL(x) x.begin(), x.end()

const long double PI = 4.0 * atan(1.0);
const long double EPS = 1e-9;

#define MAGIC 347
#define SINF 10007
#define CO 1000007
#define INF 1000000007
#define BIG 1000000931
#define LARGE 1696969696967ll
#define GIANT 2564008813937411ll
#define LLINF 2696969696969696969ll
#define MAXN 600013

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<ld> vd;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
typedef vector<pdd> vpd;


int N, M;
int arr[MAXN];
pii swp[MAXN];
vpi ans;
int ord[MAXN], rord[MAXN], val[MAXN], pos[MAXN];

void sw(int p, int q, bool flag)
{
	//POSITION p, q!
	swap(val[p], val[q]);
	swap(pos[val[p]], pos[val[q]]);
	if (!flag)
	{
		swap(rord[p], rord[q]);
		swap(ord[rord[p]], ord[rord[q]]);
	}
	else
	{
		ans.PB({p, q});
	}
	// cerr << "state:\n";
	// FOR(i, 0, N)
	// {
	// 	cerr << rord[i] << ' ';
	// }
	// cerr << endl;
	// FOR(i, 0, N)
	// {
	// 	cerr << val[i] << ' ';
	// }
	// cerr << endl;
	// cerr << p << ' ' << q << endl;
}
bool check(int x)
{
	FOR(i, 0, N)
	{
		ord[i] = i;
		rord[i] = i;
		val[i] = arr[i];
		pos[arr[i]] = i;
	}
	FORD(i, x, 0)
	{
		//ord: a[i] = x => the one that will end up at position i is currently at x
		//rord: a[i] = x => the one that is currently at i will end up at position x
		pii p = swp[i];
		swap(rord[p.fi], rord[p.se]);
		swap(ord[rord[p.fi]], ord[rord[p.se]]);
	}
	// cerr << "state:\n";
	// FOR(i, 0, N)
	// {
	// 	cerr << rord[i] << ' ';
	// }
	// cerr << endl;
	// FOR(i, 0, N)
	// {
	// 	cerr << arr[i] << ' ';
	// }
	// cerr << endl;
	// FOR(i, 0, N)
	// {
	// 	cerr << ord[i] << ' ';
	// }
	// cerr << endl;
	ans.clear();
	int iter = 0;
	FOR(i, 0, x)
	{
		pii p = swp[i];
		sw(p.fi, p.se, 0);
		while (iter < N && rord[pos[iter]] == iter)
		{
			iter++;
		}
		// DBG(iter);
		if (iter == N)
		{
			int x = randomize(N);
			ans.PB({x, x});
			continue;
		}
		sw(pos[iter], ord[iter], 1);
	}
	return (iter == N);
}
int findSwapPairs(int n, int s[], int m, int x[], int y[], int p[], int q[])
{
	N = n;
	FOR(i, 0, N)
	{
		arr[i] = s[i];
	}
	M = m;
	FOR(i, 0, M)
	{
		swp[i] = {x[i], y[i]};
	}
	check(3);
	FOR(i, 0, SZ(ans))
	{
		p[i] = ans[i].fi;
		q[i] = ans[i].se;
	}
	return SZ(ans);
	int lo = 0, hi = M;
	while(hi > lo)
	{
		int mid = (hi + lo) >> 1;
		if (check(mid))
		{
			hi = mid;
		}
		else
		{
			lo = mid + 1;
		}
	}
	check(lo);
	FOR(i, 0, SZ(ans))
	{
		p[i] = ans[i].fi;
		q[i] = ans[i].se;
	}
	return SZ(ans);
}

Compilation message (stderr)

sorting.cpp: In function 'bool check(int)':
sorting.cpp:180:8: warning: declaration of 'int x' shadows a parameter [-Wshadow]
    int x = randomize(N);
        ^
sorting.cpp:134:16: note: shadowed declaration is here
 bool check(int x)
                ^

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