Pair Of Shoes

Yesterday you found some shoes in your room. Each shoe is described by two values:

type indicates if it's a left or a right shoe;
size is the size of the shoe.
Your task is to check whether it is possible to pair the shoes you found in such a way that each pair consists of a right and a left shoe of an equal size.

Example
For:

shoes = [[0, 21], 
         [1, 23], 
         [1, 21], 
         [0, 23]]
the output should be true;

For:

shoes = [[0, 21], 
         [1, 23], 
         [1, 21], 
         [1, 23]]
the output should be false.

Input/Output
[input] 2D integer array shoes
Array of shoes. Each shoe is given in the format [type, size], where type is either 0 or 1 for left and right respectively, and size is a positive integer.

Constraints: 2 ≤ shoes.length ≤ 50,  1 ≤ shoes[i][1] ≤ 100.

[output] a boolean value

true if it is possible to pair the shoes, false otherwise.

Solution

function pairOfShoes(shoes) {
 const result = shoes.reduce((acc, [side, size]) => {
  const action = side ? 1 : -1
   
  acc[size]
    ? acc[size] += action
    : acc[size] = action
     
  return acc;
 }, {});

 return Object
  .values(result)
  .every((item) => item === 0);
}