palindrome-pairs

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python

python3

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oraclesql

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kotlin

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cangjie

Algorithms

You are given a 0-indexed array of unique strings <code>words</code>.

A palindrome pair is a pair of integers <code>(i, j)</code> such that:

<ul>
	<li><code>0 &lt;= i, j &lt; words.length</code>,</li>
	<li><code>i != j</code>, and</li>
	<li><code>words[i] + words[j]</code> (the concatenation of the two strings) is a palindrome.</li>
</ul>

Return an array of all the palindrome pairs of <code>words</code>.

You must write an algorithm with&nbsp;<code>O(sum of words[i].length)</code>&nbsp;runtime complexity.

&nbsp;
Example 1:

<pre>
Input: words = [&quot;abcd&quot;,&quot;dcba&quot;,&quot;lls&quot;,&quot;s&quot;,&quot;sssll&quot;]
Output: [[0,1],[1,0],[3,2],[2,4]]
Explanation: The palindromes are [&quot;abcddcba&quot;,&quot;dcbaabcd&quot;,&quot;slls&quot;,&quot;llssssll&quot;]
</pre>

Example 2:

<pre>
Input: words = [&quot;bat&quot;,&quot;tab&quot;,&quot;cat&quot;]
Output: [[0,1],[1,0]]
Explanation: The palindromes are [&quot;battab&quot;,&quot;tabbat&quot;]
</pre>

Example 3:

<pre>
Input: words = [&quot;a&quot;,&quot;&quot;]
Output: [[0,1],[1,0]]
Explanation: The palindromes are [&quot;a&quot;,&quot;a&quot;]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
	<li><code>0 &lt;= words[i].length &lt;= 300</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

palindromePairs

Palindrome Pairs

Longest Palindromic Substring

longest-palindromic-substring

最长回文子串

Shortest Palindrome

shortest-palindrome

最短回文串

Longest Palindrome by Concatenating Two Letter Words

longest-palindrome-by-concatenating-two-letter-words

连接两字母单词得到的最长回文串

Find Maximum Number of String Pairs

find-maximum-number-of-string-pairs

最大字符串配对数目

Trie

Array

Hash Table

String

给定一个由唯一字符串构成的 0 索引&nbsp;数组 <code>words</code>&nbsp;。

回文对 是一对整数 <code>(i, j)</code> ，满足以下条件：

<ul>
	<li><code>0 &lt;= i, j &lt; words.length</code>，</li>
	<li><code>i != j</code> ，并且</li>
	<li><code>words[i] + words[j]</code>（两个字符串的连接）是一个回文串。</li>
</ul>

返回一个数组，它包含&nbsp;<code>words</code> 中所有满足 回文对 条件的字符串。

你必须设计一个时间复杂度为 <code>O(sum of words[i].length)</code> 的算法。

&nbsp;

示例 1：

<pre>
输入：words = ["abcd","dcba","lls","s","sssll"]
输出：[[0,1],[1,0],[3,2],[2,4]] 
解释：可拼接成的回文串为 <code>["dcbaabcd","abcddcba","slls","llssssll"]</code>
</pre>

示例 2：

<pre>
输入：words = ["bat","tab","cat"]
输出：[[0,1],[1,0]] 
解释：可拼接成的回文串为 <code>["battab","tabbat"]</code></pre>

示例 3：

<pre>
输入：words = ["a",""]
输出：[[0,1],[1,0]]
</pre>
&nbsp;

提示：

<ul>
	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
	<li><code>0 &lt;= words[i].length &lt;= 300</code></li>
	<li><code>words[i]</code> 由小写英文字母组成</li>
</ul>