Beginner_Series3.js

// Kata link:
// https://www.codewars.com/kata/55f2b110f61eb01779000053/

// -------------------------------------
// Instructions:
/*

Given two integers a and b, which can be positive or negative, find the sum of all the numbers between including them too and return it. If the two numbers are equal return a or b.

Note: a and b are not ordered!

Examples
  GetSum(1, 0) == 1   // 1 + 0 = 1
  GetSum(1, 2) == 3   // 1 + 2 = 3
  GetSum(0, 1) == 1   // 0 + 1 = 1
  GetSum(1, 1) == 1   // 1 Since both are same
  GetSum(-1, 0) == -1 // -1 + 0 = -1
  GetSum(-1, 2) == 2  // -1 + 0 + 1 + 2 = 2
*/

// -------------------------------------
// Solution 1:

function getSum(a, b) {
  if (a == b) {
    return a;
  }
  let min = Math.min(a, b);
  let max = Math.max(a, b);
  return (max - min + 1) * (min + max) / 2;
}


// -------------------------------------
// Basic Tests
console.log(getSum(0, -1) == -1);
console.log(getSum(0, 1) == 1);