Help me in solving SHUFFLE problem

help
,
1

My issue

My code

#include<bits/stdc++.h>
#include <iostream>
using namespace std;
// #define ll long long int
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin>>t;
    while(t--)
    {
    long long int n, k;
    cin>>n>>k;
    long long int a[n];
    for( int i=0;i<n;i++)
    {
        cin>>a[i];
    }
    //step--1
    vector<vector<long long int >>make_array(k);
    for(int i=0;i<n;i++)
    {
        make_array[i%k].push_back(a[i]);
    }
    //step--2
    int size=make_array.size();
    for(int i=0;i<size;i++)
    {
        if(make_array[i].size()>0)
        sort(make_array[i].begin(),make_array[i].end());
    }
    //step-3
    long long int answer[n];
    for(int i=0;i<n;i++)
    {
        if(make_array[i].size()>0)
        {
            int start=i;
            for(int j=0;j<make_array[i].size();j++)
            {
              answer[start]=make_array[i][j];
              start=i+k;
            }            
        }
    }
  int check=0;
  for(int i=0;i<n-1;i++)
  {
      if(answer[i]<=answer[i+1])
      check++;
      
  }
  if(check==n-1)
  {
      cout<<"yes"<<endl;
  }
  else
  {
      cout<<"no"<<endl;
  }
    
    }
	return 0;
}

Problem Link: SHUFFLE Problem - CodeChef