candy.js

/**
 * @param {number[]} ratings
 * @return {number}
 */
var candy = function(ratings) {
    const isHigherValues = ratings.map((rating, index) => {
        return rating > (ratings[index - 1] || 10000000) || rating > (ratings[index + 1] || 10000000)
    })
        
    const isHigherGroups = isHigherValues.reduce((prev, isHigher) => {
        const topArray = prev.slice(-1)[0];
        const isHigherInPrevGroup = topArray[0]
        
        if(isHigherInPrevGroup == null) {
            topArray.push(isHigher)
        }
        else if(isHigherInPrevGroup  === isHigher) {
            topArray.push(isHigher)
        }
        else {
            const newArray = [];
            newArray.push(isHigher);
            prev.push(newArray);
        }
        
        return prev;
    }, [[]])
    
    const candies = isHigherGroups.flatMap((isHigherGroup) => {
        const isHigher = isHigherGroup[0];
        if(isHigher) {
            return Array.from({length: isHigherGroup.length}, (_, i) => i + 2).reverse();
        }
        return isHigherGroup.map(() => 1);
    })
    return candies
};