846-Hand-of-Straights.js

/**
 * https://leetcode.com/problems/hand-of-straights/
 * Time O(N * K) | Space O(N)
 * @param {number[]} hand
 * @param {number} groupSize
 * @return {boolean}
 */
 var isNStraightHand = function (hand, groupSize, count = new Map()) {
    const map = getFrequencyMap(hand);/* Time O(N) | Space O(N) */
    const sortUniqHand = getUniqueHand(hand);/* Time O(N * Log(N)) | Space O(N) */

    return search(groupSize, map, sortUniqHand);/* Time O(N * K) */
};

const getFrequencyMap = (hand, map = new Map()) => {
    for (const _hand of hand) {/* Time O(N) */
        const val = (map.get(_hand) || 0) + 1;

        map.set(_hand, val);/* Space O(N) */
    }
    
    return map;
}

const getUniqueHand = (hand) => [ ...new Set(hand) ]/* Time O(N) | Space O(N) */
    .sort((a, b) => b - a);/* Time O(N * Log(N)) | Space HeapSort O(1) | Space QuickSort O(log(N)) */

const search = (groupSize, map, sortUniqHand) => {
    while (sortUniqHand.length) {/* Time O(N) */
        const smallest = sortUniqHand[sortUniqHand.length - 1];
    
        for (let i = smallest; i < smallest + groupSize; i++) {/* Time O(K) */
            if (!map.has(i)) return false;

            const val = map.get(i) - 1;
            
            map.set(i, val);
            
            let isEqual = map.get(i) === 0;
            if (!isEqual) continue;
                
            isEqual = i === sortUniqHand[sortUniqHand.length - 1];
            if (!isEqual) return false;

            sortUniqHand.pop();
        }
    }
    
    return true;
}