# 942. DI String Match

A permutation `perm` of `n + 1` integers of all the integers in the range `[0, n]` can be represented as a string `s` of length `n` where:

• `s[i] == 'I'` if `perm[i] < perm[i + 1]`, and
• `s[i] == 'D'` if `perm[i] > perm[i + 1]`.

Given a string `s`, reconstruct the permutation `perm` and return it. If there are multiple valid permutations perm, return any of them.

Example 1:

`Input: s = "IDID"Output: [0,4,1,3,2]`

Example 2:

`Input: s = "III"Output: [0,1,2,3]`

Example 3:

`Input: s = "DDI"Output: [3,2,0,1]`

Constraints:

• `1 <= s.length <= 105`
• `s[i]` is either `'I'` or `'D'`.

# 590. N-ary Tree Postorder Traversal

Given the `root` of an n-ary tree, return the postorder traversal of its nodes' values.

Nary-Tree input serialization is represented in their level order traversal. Each group of children is separated by the null value (See examples)

Example 1:

`Input: root = [1,null,3,2,4,null,5,6]Output: [5,6,3,2,4,1]`

Example 2:

`Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]Output: [2,6,14,11,7,3,12,8,4,13,9,10,5,1]`

Constraints:

• The number of nodes in the tree is in the range `[0, 104]`.
• `0 <= Node.val <= 104`
• The height of the n-ary tree is less than or equal to `1000`.