Sorting

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

map<vector<int>, bool> possible;

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);
    vector<int> a;
    queue<vector<int>> q;
    int n;
    for(int i=1; i<=8; ++i){
        a.push_back(i);
        q.push(a);
        possible[a] = true;
    }
    while(!q.empty()){
        vector<int> u = q.front(); q.pop();
        n = u.size();
        for(int i=0; i+1<n; ++i){
            for(int j=i+2; j+1<n; ++j){
                swap(u[i], u[j]);
                swap(u[i+1], u[j+1]);
                if(!possible[u]){
                    possible[u] = true;
                    q.push(u);
                }
                swap(u[i], u[j]);
                swap(u[i+1], u[j+1]);
            }
        }
    }


    int t; cin >> t;
    while (t--) {
        cin >> n;
        vector<int> b(n);
        for(int i=0; i<n; ++i) cin >> b[i];
        cout << (possible[b] ? "YES\n" : "NO\n");
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: WRONG ANSWER

Test 3

Group: 1, 2

Verdict: ACCEPTED

Test 4

Group: 1, 2

Verdict: ACCEPTED