Array Pair Sum Divisibility Problem Geeks solution

Array Pair Sum Divisibility Problem Geeks solution

  July 23, 2017    

---

Problem :

Given an array of integers and a number k, write a function that prints True if given array can be divided into pairs such that sum of every pair is divisible by k.

Idea is to save remainder in a hashmap (key as no. of elements) Check whether the remainder is 0 or remainder is half of k means the number is completely divisible and another same  number  should also be there so check for it
Check if remainder and k-rem are there with equal numbers 

code

import java.util.*;
import java.lang.*;
import java.io.*;
class hackerranksolutionc
 {
public static void main (String[] args)
{
Scanner ab=new Scanner(System.in);
int t=ab.nextInt();
st:
while(t-->0)
{
   int n=ab.nextInt();
   Map<Integer,Integer> hmap=new HashMap<Integer,Integer>();
   hmap.clear();
   int arr[]=new int[n];
   for(int i=0;i<n;i++)
  { arr[i]=ab.nextInt();
      
  }
   int k=ab.nextInt();
   
   if(n%2==1)
   {
       System.out.println("False");
       continue st;
   }
   for(int i=0;i<n;i++)
   {
       if(hmap.containsKey(arr[i]%k))
      hmap.put(arr[i]%k,hmap.get(arr[i]%k)+1);
      else
      hmap.put(arr[i]%k,1);
   }
   for(int i=0;i<n;i++)
   {
   int rem=arr[i]%k;
   if(rem==0 || 2*rem==k)
  { if(hmap.get(rem)%2==1)
   {
       System.out.println("False");
       continue st;
}}
else if(hmap.get(rem)!=hmap.get(k-rem))
{
   System.out.println("False");
       continue st;
}
}
System.out.println("True");
}}}