Submission #387262

#	Time	Username	Problem	Language	Result	Execution time	Memory
387262		ParsaAlizadeh	Sorting (IOI15_sorting)	C++17	100 / 100	204 ms	22600 KiB

sorting

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

typedef pair<int, int> pii;

vector<int> perm;
vector<pii> alice, bob;

bool check(int t) {
	vector<int> tmp(perm);
	for (int i = 0; i < t; i++) {
		swap(tmp[alice[i].first], tmp[alice[i].second]);
	}
	bob.clear();
	for (int i = 0; i < tmp.size(); i++) {
		while (tmp[i] != i) {
			bob.emplace_back(tmp[i], tmp[tmp[i]]);
			swap(tmp[i], tmp[tmp[i]]);
		}
	}
	while (bob.size() < t)
		bob.emplace_back(0, 0);
	return bob.size() == t;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	perm.assign(S, S + N);
	for (int i = 0; i < M; i++) {
		alice.emplace_back(X[i], Y[i]);
	}
	int L = -1, R = M;
	while (R - L > 1) {
		int mid = (L + R) >> 1;
		(check(mid) ? R : L) = mid;
	}
	check(R);
	vector<int> inv(N);
	for (int i = 0; i < N; i++) {
		inv[perm[i]] = i;
	}
	const auto replc = [&] (int i, int j) {
		swap(perm[i], perm[j]);
		inv[perm[i]] = i;
		inv[perm[j]] = j;
	};
	for (int i = 0; i < R; i++) {
		replc(X[i], Y[i]);
		P[i] = inv[bob[i].first];
		Q[i] = inv[bob[i].second];
		replc(P[i], Q[i]);
	}
	return R;
}

Compilation message (stderr)

sorting.cpp: In function 'bool check(int)':
sorting.cpp:16:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   16 |  for (int i = 0; i < tmp.size(); i++) {
      |                  ~~^~~~~~~~~~~~
sorting.cpp:22:20: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   22 |  while (bob.size() < t)
      |         ~~~~~~~~~~~^~~
sorting.cpp:24:20: warning: comparison of integer expressions of different signedness: 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   24 |  return bob.size() == t;
      |         ~~~~~~~~~~~^~~~

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