Submission #1018724

#	Time	Username	Problem	Language	Result	Execution time	Memory
1018724		AmirAli_H1	Sorting (IOI15_sorting)	C++17	74 / 100	1038 ms	16212 KiB

sorting

// In the name of Allah

#include <bits/stdc++.h>
#include "sorting.h"
using namespace std;

typedef		long long int			ll;
typedef		long double				ld;
typedef		pair<int, int>			pii;
typedef		pair<ll, ll>			pll;
typedef		complex<ld>				cld;

#define		all(x)					(x).begin(),(x).end()
#define		len(x)					((ll) (x).size())
#define		F						first
#define		S						second
#define		pb						push_back
#define		sep						' '
#define		endl					'\n'
#define		Mp						make_pair
#define		kill(x)					cout << x << '\n', exit(0)
#define		set_dec(x)				cout << fixed << setprecision(x);
#define		file_io(x,y)			freopen(x, "r", stdin); freopen(y, "w", stdout);
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n, q;
const int maxn = 2e5 + 7;
int A1[maxn], A2[maxn], mark[maxn];

void dfs(int v) {
	mark[v] = 1; int u = A1[v];
	if (!mark[u]) dfs(u);
}

bool ok(int n, int S[], int q, int X[], int Y[]) {
	for (int i = 0; i < n; i++) A1[i] = S[i];
	for (int i = 0; i < q; i++) {
		int i1 = X[i], i2 = Y[i];
		swap(A1[i1], A1[i2]);
	}
	fill(mark, mark + n, 0); int c = 0;
	for (int i = 0; i < n; i++) {
		if (!mark[i]) {
			dfs(i); c++;
		}
	}
	return (n - c <= q);
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
    int l = -1, r = M;
	while (r - l > 1) {
		int mid = (l + r) / 2;
		if (ok(N, S, mid, X, Y)) r = mid;
		else l = mid;
	}
	n = N; q = r;
    
    for (int i = 0; i < n; i++) {
    	A1[i] = S[i]; A2[i] = S[i];
	}
	for (int i = 0; i < q; i++) {
		int i1 = X[i], i2 = Y[i];
		P[i] = 0; Q[i] = 0;
		swap(A2[i1], A2[i2]);
	}
	
	for (int i = 0; i < q; i++) {
		int i1 = X[i], i2 = Y[i];
		swap(A1[i1], A1[i2]);
		int x1 = -1, x2 = -1;
		for (int j = 0; j < n; j++) {
			if (A2[j] != j) {
				x1 = A2[j], x2 = A2[A2[j]];
				swap(A2[j], A2[A2[j]]);
				break;
			}
		}
		if (x1 != -1 && x2 != -1) {
			P[i] = find(A1, A1 + n, x1) - A1;
			Q[i] = find(A1, A1 + n, x2) - A1;
		}
		i1 = P[i], i2 = Q[i];
		swap(A1[i1], A1[i2]);
	}
	return q;
}

Compilation message (stderr)

sorting.cpp: In function 'bool ok(int, int*, int, int*, int*)':
sorting.cpp:35:29: warning: declaration of 'q' shadows a global declaration [-Wshadow]
   35 | bool ok(int n, int S[], int q, int X[], int Y[]) {
      |                         ~~~~^
sorting.cpp:26:8: note: shadowed declaration is here
   26 | int n, q;
      |        ^
sorting.cpp:35:13: warning: declaration of 'n' shadows a global declaration [-Wshadow]
   35 | bool ok(int n, int S[], int q, int X[], int Y[]) {
      |         ~~~~^
sorting.cpp:26:5: note: shadowed declaration is here
   26 | int n, q;
      |     ^
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:80:32: warning: conversion from 'long int' to 'int' may change value [-Wconversion]
   80 |    P[i] = find(A1, A1 + n, x1) - A1;
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~
sorting.cpp:81:32: warning: conversion from 'long int' to 'int' may change value [-Wconversion]
   81 |    Q[i] = find(A1, A1 + n, x2) - A1;
      |           ~~~~~~~~~~~~~~~~~~~~~^~~~

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