LeetCode in Elixir

131. Palindrome Partitioning

Medium

Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s.

A palindrome string is a string that reads the same backward as forward.

Example 1:

Input: s = “aab”

Output: [[“a”,”a”,”b”],[“aa”,”b”]]

Example 2:

Input: s = “a”

Output: [[“a”]]

Constraints:

• 1 <= s.length <= 16
• s contains only lowercase English letters.

Solution

defmodule Solution do
  use Agent

  @spec partition(s :: String.t()) :: [[String.t()]]
  def partition(s) do
    dfs(s, String.length(s), 0, [], [])
  end

  def dfs(_s, len, l, subs, ans) when l == len do
    [Enum.reverse(subs) | ans]
  end

  def dfs(s, len, l, subs, ans) do
    l..(len - 1)
    |> Enum.reduce(ans, fn r, ans ->
      ss = String.slice(s, l..r)

      if ss == String.reverse(ss) do
        dfs(s, len, r + 1, [ss | subs], ans)
      else
        ans
      end
    end)
  end
end

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