1022-smallest-integer-divisible-by-k.js

/**
 * @param {number} K
 * @return {number}
 */
const smallestRepunitDivByK = function(K) {
    if (K % 2 === 0 || K % 5 === 0) return -1;
    let r = 0;
    for (let N = 1; N <= K; ++N) {
        r = (r * 10 + 1) % K;
        if (r == 0) return N;
    }
    return -1;
};