function solution(s) { if (s.length !== 4 && s.length !== 6) return false; return [...s].every(e => +e >= 0); }

function solution(s) { return [...s].sort().reverse().join(''); }

function solution(s) { if (!s) return true; let cntOfP = 0; let cntOfY = 0; [...s.toUpperCase()].forEach(word => { word === 'P' ? ++cntOfP : word === 'Y' ? ++cntOfY : null; }); return cntOfP === cntOfY ? true : false; }

function solution(strings, n) { return strings.sort((a, b) => (a[n] === b[n] ? a.localeCompare(b) : a[n].localeCompare(b[n]))); }

function solution(a, b) { if (a === b) return a; const startNum = a < b ? a : b; const endNum = a < b ? b : a; let result = 0; for (let i = startNum; i

function solution(arr, divisor) { const result = arr.filter(e => e % divisor === 0); return result.length ? result.sort((a, b) => a - b) : [-1]; }

function solution(arr) { return arr.filter((_, i) => arr[i] !== arr[i - 1]); }

function solution(s) { return s.length % 2 ? s.substr(s.length / 2, 1) : s.substr(s.length / 2 - 1, 2); }