There are n children standing in a line. Each child is assigned a rating value given in the integer array ratings. You are giving candies to these children subjected to the following requirements: Each child must have at least one candy. Children w

candy.js

/**
 * @param {number[]} ratings
 * @return {number}
 */
var candy = function(ratings) {
    const length = ratings.length;

    // Initialize candies array, giving each child at least one candy.
    const candies = new Array(length).fill(1);

    // Forward pass: ensure children with higher ratings than their left neighbor get more candies.
    for (let i = 1; i < length; i++) {
        if (ratings[i] > ratings[i - 1]) {
            candies[i] = candies[i - 1] + 1;
        }
    }

    // Backward pass: ensure children with higher ratings than their right neighbor get more candies.
    for (let i = length - 2; i >= 0; i--) {
        if (ratings[i] > ratings[i + 1]) {
            // Take the maximum of current candies or candies required for the right neighbor.
            candies[i] = Math.max(candies[i], candies[i + 1] + 1);
        }
    }

    // Sum up the total candies needed.
    return candies.reduce((total, candyCount) => total + candyCount, 0);
};