{ "data": { "question": { "questionId": "2237", "questionFrontendId": "2131", "categoryTitle": "Algorithms", "boundTopicId": 1196698, "title": "Longest Palindrome by Concatenating Two Letter Words", "titleSlug": "longest-palindrome-by-concatenating-two-letter-words", "content": "

You are given an array of strings words. Each element of words consists of two lowercase English letters.

\n\n

Create the longest possible palindrome by selecting some elements from words and concatenating them in any order. Each element can be selected at most once.

\n\n

Return the length of the longest palindrome that you can create. If it is impossible to create any palindrome, return 0.

\n\n

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

\n\n

 

\n

Example 1:

\n\n
\nInput: words = ["lc","cl","gg"]\nOutput: 6\nExplanation: One longest palindrome is "lc" + "gg" + "cl" = "lcggcl", of length 6.\nNote that "clgglc" is another longest palindrome that can be created.\n
\n\n

Example 2:

\n\n
\nInput: words = ["ab","ty","yt","lc","cl","ab"]\nOutput: 8\nExplanation: One longest palindrome is "ty" + "lc" + "cl" + "yt" = "tylcclyt", of length 8.\nNote that "lcyttycl" is another longest palindrome that can be created.\n
\n\n

Example 3:

\n\n
\nInput: words = ["cc","ll","xx"]\nOutput: 2\nExplanation: One longest palindrome is "cc", of length 2.\nNote that "ll" is another longest palindrome that can be created, and so is "xx".\n
\n\n

 

\n

Constraints:

\n\n\n", "translatedTitle": "连接两字母单词得到的最长回文串", "translatedContent": "

给你一个字符串数组 words 。words 中每个元素都是一个包含 两个 小写英文字母的单词。

\n\n

请你从 words 中选择一些元素并按 任意顺序 连接它们,并得到一个 尽可能长的回文串 。每个元素 至多 只能使用一次。

\n\n

请你返回你能得到的最长回文串的 长度 。如果没办法得到任何一个回文串,请你返回 0 。

\n\n

回文串 指的是从前往后和从后往前读一样的字符串。

\n\n

 

\n\n

示例 1:

\n\n
输入:words = [\"lc\",\"cl\",\"gg\"]\n输出:6\n解释:一个最长的回文串为 \"lc\" + \"gg\" + \"cl\" = \"lcggcl\" ,长度为 6 。\n\"clgglc\" 是另一个可以得到的最长回文串。\n
\n\n

示例 2:

\n\n
输入:words = [\"ab\",\"ty\",\"yt\",\"lc\",\"cl\",\"ab\"]\n输出:8\n解释:最长回文串是 \"ty\" + \"lc\" + \"cl\" + \"yt\" = \"tylcclyt\" ,长度为 8 。\n\"lcyttycl\" 是另一个可以得到的最长回文串。\n
\n\n

示例 3:

\n\n
输入:words = [\"cc\",\"ll\",\"xx\"]\n输出:2\n解释:最长回文串是 \"cc\" ,长度为 2 。\n\"ll\" 是另一个可以得到的最长回文串。\"xx\" 也是。
\n\n

 

\n\n

提示:

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Suppose we have a palindrome. If we prepend the word \"ab\" on the left, what must we append on the right to keep it a palindrome?", "We must append \"ba\" on the right. The number of times we can do this is the minimum of (occurrences of \"ab\") and (occurrences of \"ba\").", "For words that are already palindromes, e.g. \"aa\", we can prepend and append these in pairs as described in the previous hint. We can also use exactly one in the middle to form an even longer palindrome." ], "solution": null, "status": null, "sampleTestCase": "[\"lc\",\"cl\",\"gg\"]", "metaData": "{\n \"name\": \"longestPalindrome\",\n \"params\": [\n {\n \"name\": \"words\",\n \"type\": \"string[]\"\n }\n ],\n \"return\": {\n \"type\": \"integer\"\n }\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "envInfo": "{\"cpp\":[\"C++\",\"

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