Submission #1090965

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090965		owoovo	Sorting (IOI15_sorting)	C++17	74 / 100	205 ms	15952 KiB

sorting

#include "sorting.h"
#include<bits/stdc++.h>
using namespace std;
int tar[1000010],tarp[1000010],n,x[1000010],y[1000010],s[1000010];

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
	n=N;
	for(int i=0;i<M;i++){
		x[i+1]=X[i];
		y[i+1]=Y[i];
	}
	int l=0,r=M;
	while(l!=r){
		int m=(l+r)>>1,ok=1;
		//cout<<l<<" "<<r<<" "<<m<<"\n";
		for(int i=0;i<N;i++){
			tar[i]=i;
			s[i]=S[i];
		}
		for(int i=m;i>0;i--){
			swap(tar[x[i]],tar[y[i]]);
		}
		for(int i=0;i<N;i++){
			tarp[tar[i]]=i;
		}
		int ans=0;
		for(int i=0;i<N;i++){
			if(s[i]==tar[i])continue;
			int ori=i;
			while(tarp[s[ori]]!=ori){
				P[ans]=tarp[s[ori]];
				Q[ans]=ori;
				swap(s[tarp[s[ori]]],s[ori]);
				ans++;
			}
		}
		if(ans>m){
			l=m+1;
		}else{
			r=m;
		}
	}

	int m=l;
	for(int i=0;i<N;i++){
		tar[i]=i;
		s[i]=S[i];
	}
	for(int i=m;i>0;i--){
		swap(tar[x[i]],tar[y[i]]);
	}
	for(int i=0;i<N;i++){	
		tarp[tar[i]]=i;
	}
	if(m!=0){
		swap(tar[x[1]],tar[y[1]]);
		swap(s[x[1]],s[y[1]]);
		tarp[tar[x[1]]]=x[1];
		tarp[tar[y[1]]]=y[1];
	}
	int ans=0;
	for(int i=0;i<N;i++){
		//cout<<s[i]<<" "<<tar[i]<<"\n";
		if(s[i]==tar[i])continue;
		int ori=i;
		while(ori!=tarp[s[ori]]){
			//cout<<now<<" "<<ori<<"\n";
			P[ans]=tarp[s[ori]];
			Q[ans]=ori;
			swap(s[tarp[s[ori]]],s[ori]);
			ans++;
			if(ans>=m)break;
			if(ori==x[ans+1])ori=y[ans+1];
			else if(ori==y[ans+1])ori=x[ans+1];
			swap(tar[x[ans+1]],tar[y[ans+1]]);
			swap(s[x[ans+1]],s[y[ans+1]]);
			tarp[tar[x[ans+1]]]=x[ans+1];
			tarp[tar[y[ans+1]]]=y[ans+1];
		}
		if(ans>=m)break;
	}
	for(int i=0;i<N;i++){
		if(s[i]!=tar[i]){
			cout<<"?\n";
		}
	}
	for(int i=ans;i<m;i++)Q[i]=0,P[i]=0;
	return l;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:14:18: warning: unused variable 'ok' [-Wunused-variable]
   14 |   int m=(l+r)>>1,ok=1;
      |                  ^~

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