Cassidy Williams - question of the week 2021-05-09

whoOwes.js

const whoOwes = (receipts) => {
  const people = {};
  let total = 0;

  for (const { name, paid } of receipts) {
    people[name] = people[name] === undefined ? paid : people[name] + paid;
    total += paid;
  }

  const totalEach = Math.floor(total * 100 / Object.keys(people).length) / 100; // Divide with cents
  const owesList = [];
  const owedList = [];
  const result = [];
  for (const person of Object.keys(people)) {
    const tripResult = people[person] - totalEach;
    if (tripResult > 0) {
      owedList.push({ name: person, owed: tripResult });
    } else if (tripResult < 0) {
      owesList.push({ name: person, owes: tripResult });
    }
  }

  for (let { name, owes } of owesList) {
    while (owes < 0) {
      const oP = owedList.at(-1);
      if (Math.abs(owes) >= oP.owed) {
        result.push(`${name} owes ${oP.name} $${oP.owed}`);
        owedList.pop();
        owes += oP.owed;
      } else {
        result.push(`${name} owes ${oP.name} $${Math.abs(owes)}`);
        owedList.at(-1).owed += owes;
        owes = 0;
      }
    }
  }

  return result.join(', ');
};

let receipts = [
  { name: 'Ximena', paid: 45 },
  { name: 'Clara', paid: 130 },
  { name: 'Ximena', paid: 100 },
  { name: 'Cassidy', paid: 140 },
  { name: 'Cassidy', paid: 76 },
  { name: 'Clara', paid: 29 },
  { name: 'Ximena', paid: 20 },
];

console.log(whoOwes(receipts));