Sorting

input/code.cpp: In function 'int main()':
input/code.cpp:39:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
      for(int l=0; l<v.size(); ++l){
                   ~^~~~~~~~~

#define MOD 1000000007
#include <bits/stdc++.h>
#include <numeric>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	array<set<vector<int>>,8> arr;
	queue<int> q;
	set<int> vis;
	for(int i=1; i<=8; ++i){
		int n=0;
		for(int j=1; j<=i; ++j){
			n*=10;
			n+=j;
		}
		q.push(n);
		vis.insert(n);
		while(!q.empty()){
			n=q.front();
			q.pop();
			vector<int> v;
			while(n){
				v.push_back(n%10);
				n/=10;
			}
			reverse(v.begin(),v.end());
			arr[i-1].insert(v);
			for(int j=0; j<i-3; ++j){
				for(int k=j+2; k<i-1; ++k){
					swap(v[j],v[k]);
					swap(v[j+1],v[k+1]);
					n=0;
					for(int l=0; l<v.size(); ++l){
						n*=10;
						n+=v[l];
					}
					if(vis.find(n)==vis.end()){
						vis.insert(n);
						q.push(n);
					}
					swap(v[j],v[k]);
					swap(v[j+1],v[k+1]);
				}
			}
		}
	}
	int T;
	cin>>T;
	for(int T_Case=1;T_Case<=T;++T_Case){
		int n,c{0};
		cin>>n;
		vector<int> a(n);
		for(int i=0; i<n; ++i){
			cin>>a[i];
			for(int j=0; j<i; ++j){
				c+=a[j]>a[i];
			}
		}
		if(n<=8){
			if(arr[n-1].find(a)!=arr[n-1].end()){
				cout<<"YES"<<'\n';
			}
			else{
				cout<<"NO"<<'\n';
			}
		}
		else{
			if(c%2==0){
				cout<<"YES"<<'\n';
			}
			else{
				cout<<"NO"<<'\n';
			}
		}
	}
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED