From Codility

In this puzzle, we are given an input list of numbers and these numbers can be negative or positive and we need to find two of these numbers represented over a year by the Pointer P and Q such that when you sum the value at P and the value of Q you get a result.
And if you put that result into an absolute function, the result will be a minimum.

Example:
console.log(solution([-7,3,-1,5,-11,-9,14,17,-2])) =>1
console.log(solution([8,3,5,16,11])) =>6

console.log(solution([-7,-5,-6,-2,-9])) =>4
console.log(solution([-7,3,-6,1,0,-9])) => 0
console.log(solution([-22,3,4,5])) => 6

function solution(input) {
  let minAbsSumOfTwo = Number.MAX_VALUE;
  input.sort((a,b) => a - b);
  let head = 0
  let tail = input.length -1;
  while(head <= tail) {
    minAbsSumOfTwo = Math.min(minAbsSumOfTwo,Math.abs(input[head]+ input[tail]));
    if(input[head] + input[tail] < 0) head ++; 
    else tail --;
  }
  return minAbsSumOfTwo;
}

console.log(solution([-7,3,-1,5,-11,-9,14,17,-2]))
console.log(solution([8,3,5,16,11]))
console.log(solution([-7,-5,-6,-2,-9]))
console.log(solution([-7,3,-6,1,0,-9]))
console.log(solution([-22,3,4,5]))

We create a function called solution with parameter called input.

First in this function we create a variable that will hold our solution and we called minAbsSumOfTwo = Number.MAX_VALUE; Number.MAX_VALUE is the number largest max integer
Then we need to sort the input like this input.sort((a, b) => )

Next we need to initialize our two pointers, the red and blue arrows and we shall call them the first one had to give its a value of 0 and the next one to be tail

First one we shall call head = 0; second tail = input.length - 1;

Next we need while loop to check while(head <= tail) { minAbsSumOfTwo = Math.min(minAbsSumOfTwo, Math.abs(input[head]+ input[tail])); if (input[head]) + input[tail] < 0) head ++; else tail–; }

While head was smaller or equal to tail we loop with while loop and inside we calculate
minAbsSumOfTwo = Math.min(minAbsSumOfTwo), Math.abs(input[head] + input[tail]);
Math.min and Math.abs are JavaScript build in methods Math.min = > The static function Math.min() returns the lowest-valued number passed into it, or NaN if any parameter isn’t a number and can’t be converted into one. [MDN]
Math.abs = > The Math.abs() function returns the absolute value of a number. That is, it returns x if x is positive or zero, and the negation of x if x is negative.[MDN]


We check if input[head] + input[tail] < 0 and if it is head ++ else tail ++
In the end we return minAbsSumOfTwo;