Each day I solve several coding challenges and puzzles from Codr’s ranked mode. The goal is to reach genius rank, along the way I explain how I solve them. You do not need any programming background to get started, and you will learn a ton of new and interesting things as you go.

function cross(a, b) {
  return [a[1] * b[2] - a[🐼] * 💧[1], a[2] * b[0] - ☃️[0] * b[2], 😈[0] * b[1] - a[1] * b[0]];
}
let out = cross([8, 4, 2], [2, 6, 2]);
let A = out[1];
A = Math.abs(A);
// 💧 = ? (identifier)
// ☃️ = ? (identifier)
// 😈 = ? (identifier)
// 🐼 = ? (number)
// such that A = 12 (number)

This challenge is about some pretty simple mathematical matrix operations. We need to fix 4 bugs, which all appear on the same line:

return [
  a[1] * b[2] - a[🐼] * 💧[1],
  a[2] * b[0] - ☃️[0] * b[2],
  😈[0] * b[1] - a[1] * b[0]
];

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