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`