Event Pair Sum (EVENPSUM)Solution — Codechef December Long Challenge

Problem Statement

You are given two positive integers A and B. Find the number of pairs of positive integers (X,Y) such that 1≤X≤A, 1≤Y≤B and X+Y is even.

Input

• The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
• The first and only line of each test case contains two space-separated integers A and B.

Output

For each test case, print a single line containing one integer ― the number of valid pairs.

Constraints

• 1≤T≤1,000
• 1≤A,B≤109

Subtasks

Subtask #1 (10 points): A,B≤10

Subtask #2 (10 points): A,B≤1,000

Subtask #3 (80 points): original constraints

Example Input

4
1 1
2 3
4 6
8 9

Example Output

1
3
12
36

Code ( Solution )

The code has been implemented in Java.

import java.util.*;
import java.lang.*;
import java.io.*;
class Codechef
{
public static void main (String[] args) throws java.lang.Exception
{
// your code goes here
Scanner sc = new Scanner (System.in);
int t = sc.nextInt();
long a,b=0;
while(t-- > 0){
long o1,o2,e1,e2 =0;
  a = sc.nextInt();
  b = sc.nextInt();
  if(a%2==0){
     e1 = a/2;
     o1 = a/2;
}
else{
  o1 = a/2 +1;
  e1 = a/2;
}
if(b%2==0)
{
  e2 = b/2;
  o2 = b/2;
}
else{
  o2 = b/2+1;
  e2 = b/2;
   }
System.out.println((o1*o2)+(e1*e2));
  }
 }
}

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Referenced Question Link

https://www.codechef.com/DEC20B/problems/EVENPSUM