{ "data": { "question": { "questionId": "336", "questionFrontendId": "336", "boundTopicId": null, "title": "Palindrome Pairs", "titleSlug": "palindrome-pairs", "content": "

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

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Example 1:

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\nInput: words = ["abcd","dcba","lls","s","sssll"]\nOutput: [[0,1],[1,0],[3,2],[2,4]]\nExplanation: The palindromes are ["dcbaabcd","abcddcba","slls","llssssll"]\n
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Example 2:

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\nInput: words = ["bat","tab","cat"]\nOutput: [[0,1],[1,0]]\nExplanation: The palindromes are ["battab","tabbat"]\n
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Example 3:

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\nInput: words = ["a",""]\nOutput: [[0,1],[1,0]]\n
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Constraints:

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