Sorting

input/code.cpp: In function 'void solve()':
input/code.cpp:48:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i",&n);
     ~~~~~^~~~~~~~~
input/code.cpp:52:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%i",&inp[i]);
         ~~~~~^~~~~~~~~~~~~~
input/code.cpp: In function 'int main()':
input/code.cpp:88:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i",&t);
     ~~~~~^~~~~~~~~

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

const int nmax=100+5;

int n,inp[nmax];

map< vector<int>, int> seen;

bool go()
{
    bool ok=1;

    for(int i=1;i<=n;i++)
        if(inp[i]!=i)ok=0;

    if(ok)return 1;

    vector<int> v={};
    for(int i=1;i<=n;i++)v.push_back(inp[i]);

    if(seen.count(v))return 0;
    seen[v]=1;

    for(int i=1;i<n;i++)
        for(int j=i+2;j<n;j++)
        {
            swap(inp[i],inp[j]);
            swap(inp[i+1],inp[j+1]);

            if(go())return 1;

            swap(inp[i],inp[j]);
            swap(inp[i+1],inp[j+1]);
        }
    return 0;
}

bool brute()
{
    seen={};

    return go();
}

void solve()
{
    scanf("%i",&n);

    for(int i=1;i<=n;i++)
    {
        scanf("%i",&inp[i]);
    }

    if(n<=6)
    {
        if(brute())
        {
            printf("YES\n");
        }
        else
        {
            printf("NO\n");
        }

        return;
    }

    int inv=0;

    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n;j++)
            if(inp[i]>inp[j])inv++;

    if(inv%2==0)
    {
        printf("YES\n");
    }
    else
    {
        printf("NO\n");
    }
}

int main()
{
    int t;
    scanf("%i",&t);

    while(t)
    {
        t--;
        solve();
    }
    return 0;
}

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