Submission #1044925

#	Time	Username	Problem	Language	Result	Execution time	Memory
1044925		mar	Xor Sort (eJOI20_xorsort)	C++14	100 / 100	41 ms	1172 KiB

xorsort

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll arr[1000007];
int main(){
	int n,s; cin>>n>>s;
	for (int i = 0; i < n; i++){
		cin>>arr[i];
	}
	vector<pair<int,int>> ans;
	if(s==2){
		for(int bit = 22; bit >= 0; bit--){
			for(int i = 0; i+1 < n; i++){
				if(arr[i]&(1LL<<bit)){
					if (arr[i+1]&(1LL<<bit)){
						ans.push_back({i+1,i+2});
						arr[i]^=arr[i+1];
					} else {
						ans.push_back({i+2,i+1});
						ans.push_back({i+1,i+2});
						arr[i+1]^=arr[i];
						arr[i]^=arr[i+1];
					}
				}
			}
			if((n>=1) && (arr[n-1]&(1LL<<bit))){
				n--;
			}
		}
	} else {
		for(int i = n; i >= 1; i--){
			int mx = 0;
			for(int j = 0; j < i; j++){
				if(arr[j]>arr[mx]) mx=j;
				if(j+1<i){
					ans.push_back({j+1,j+2});
				}
			}
			for(int j = mx-2; j >= 0; j--){
				ans.push_back({j+1,j+2});
			}
			for(int j = mx; j+1 < i; j++){
				ans.push_back({j+2,j+1});
			}
			for(int k = mx; k + 1 < i; k++){
				swap(arr[k],arr[k+1]);
			}
		}
		for(int i = n; i >= 2; i--){
			ans.push_back({i-1,i});
		}
	}
	cout<<ans.size()<<endl;
	for (int i = 0; i < ans.size(); i++){
		cout<<ans[i].first<<" "<<ans[i].second<<endl;
	}
}

Compilation message (stderr)

xorsort.cpp: In function 'int main()':
xorsort.cpp:54:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |  for (int i = 0; i < ans.size(); i++){
      |                  ~~^~~~~~~~~~~~

• Subtask 1: 25 / 25
• Subtask 2: 35 / 35
• Subtask 3: 40 / 40