Palindrome Pairs

Given a list of unique words. Find all pairs of distinct indices(i, j)
in the given list, so that the concatenation of the two words, i.e.words[i] + words[j]
is a palindrome.

• Example 1:Givenwords
  =["bat", "tab", "cat"]
  Return[[0, 1], [1, 0]]
  The palindromes are["battab", "tabbat"]

• Example 2:Givenwords
  =["abcd", "dcba", "lls", "s", "sssll"]
  Return[[0, 1], [1, 0], [3, 2], [2, 4]]
  The palindromes are["dcbaabcd", "abcddcba", "slls", "llssssll"]