LeetCode in TypeScript

135. Candy

Hard

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 with a higher rating get more candies than their neighbors.

Return the minimum number of candies you need to have to distribute the candies to the children.

Example 1:

Input: ratings = [1,0,2]

Output: 5

Explanation: You can allocate to the first, second and third child with 2, 1, 2 candies respectively.

Example 2:

Input: ratings = [1,2,2]

Output: 4

Explanation: You can allocate to the first, second and third child with 1, 2, 1 candies respectively. The third child gets 1 candy because it satisfies the above two conditions.

Constraints:

• n == ratings.length
• 1 <= n <= 2 * 104
• 0 <= ratings[i] <= 2 * 104

Solution

function candy(ratings: number[]): number {
    const n = ratings.length
    const candies: number[] = new Array(n).fill(1)
    for (let i = 0; i < n - 1; i++) {
        if (ratings[i + 1] > ratings[i]) {
            candies[i + 1] = candies[i] + 1
        }
    }
    for (let i = n - 1; i > 0; i--) {
        if (ratings[i - 1] > ratings[i] && candies[i - 1] < candies[i] + 1) {
            candies[i - 1] = candies[i] + 1
        }
    }
    return candies.reduce((sum, c) => sum + c, 0)
}

export { candy }

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