Submission #1173883

#	Time	Username	Problem	Language	Result	Execution time	Memory
1173883		HappyCapybara	Sorting (IOI15_sorting)	C++20	100 / 100	116 ms	20004 KiB

sorting

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

int solve(vector<int> v){
	vector<bool> seen(v.size(), false);
	int res = 0;
	for (int i=0; i<v.size(); i++){
		if (seen[i]) continue;
		seen[i] = true;
		int j = i;
		while (!seen[v[j]]){
			res++;
			j = v[j];
			seen[j] = true;
		}
	}
	return res;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]){
	vector<int> f(N), g(N);
	for (int i=0; i<N; i++){
		f[i] = i;
		g[i] = i;
	}
	int l = -1, r = M;
	while (l != r-1){
		int m = (l+r)/2;
		vector<int> gx = g;
		for (int i=0; i<m; i++) swap(gx[X[i]], gx[Y[i]]);
    	vector<int> v(N);
		for (int i=0; i<N; i++) v[i] = S[gx[i]];
		if (solve(v) <= m) r = m;
		else l = m;
	}
	for (int i=0; i<r; i++){
		swap(g[X[i]], g[Y[i]]);
		swap(f[g[Y[i]]], f[g[X[i]]]);
	}
	vector<int> v(N);
	for (int i=0; i<N; i++) v[i] = S[g[i]];
	unordered_set<int> us;
	for (int i=0; i<N; i++) us.insert(i);
	for (int i=0; i<r; i++){
		swap(f[X[i]], f[Y[i]]);
		swap(g[f[Y[i]]], g[f[X[i]]]);
		P[i] = 0;
		Q[i] = 0;
		vector<int> del;
		for (int j : us){
			if (v[j] == j) del.push_back(j);
			if (v[j] != j){
				P[i] = g[j];
				Q[i] = g[v[j]];
				swap(v[j], v[v[j]]);
				break;
			}
		}
		for (int j : del) us.erase(j);
	}
	return r;
}

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