<pre class="shiki github-dark shaku"><code>function decode(message) { const m = message.length; if (m === 0) return ""; const n = message[0].length; let ans = ""; let [x, y] = [0, 0]; let direction = -1; while (y &lt; n) { ans += message[x][y]; if (direction === -1) x += 1; else x -= 1; if (x === m - 1 || x === 0) direction *= -1; y += 1; } return ans;}</code></pre>