cardComparison.js

/**
 * war.js
 * Algorithm complexity might be O(n + 4). 4 Lookups + 1 Loop
 */

const CARD_ORDER = 'AKQJT98765432';

function war(handA, handB) {
  let totalScore = 0;

  for (let i = handA.length - 1; i >= 0; i--) {
    console.log(
      `handA: el: ${handA.charAt(i)} order: ${cardOrderOf(
        handA.charAt(i)
      )} VS handB: el: ${handB.charAt(i)} order: ${cardOrderOf(
        handB.charAt(i)
      )} win: ${cardOrderOf(handA.charAt(i)) <
        cardOrderOf(handB.charAt(i))} totalScore: ${totalScore}`
    );

    if (cardOrderOf(handA.charAt(i)) < cardOrderOf(handB.charAt(i))) {
      totalScore += 1;
    }
  }

  return totalScore;
}

function cardOrderOf(card) {
  return CARD_ORDER.indexOf(card);
}

console.log('AT3K2 VS QJ795:', war('AT3K2', 'QJ795')); // 2
console.log('72Q8A VS 2KQ63:', war('72Q8A', '2KQ63')); // 3 correction in the docx