{"id":7525,"date":"2020-10-18T10:39:37","date_gmt":"2020-10-18T17:39:37","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=7525"},"modified":"2020-10-18T10:40:30","modified_gmt":"2020-10-18T17:40:30","slug":"leetcode-1624-largest-substring-between-two-equal-characters","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/hashtable\/leetcode-1624-largest-substring-between-two-equal-characters\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1624. Largest Substring Between Two Equal Characters"},"content":{"rendered":"\n

Given a string s<\/code>, return the length of the longest substring between two equal characters, excluding the two characters.<\/em> If there is no such substring return -1<\/code>.<\/p>\n\n\n\n

A substring<\/strong> is a contiguous sequence of characters within a string.<\/p>\n\n\n\n

Example 1:<\/strong><\/p>\n\n\n\n

Input:<\/strong> s = \"aa\"\nOutput:<\/strong> 0\nExplanation:<\/strong> The optimal substring here is an empty substring between the two 'a's<\/code>.<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> s = \"abca\"\nOutput:<\/strong> 2\nExplanation:<\/strong> The optimal substring here is \"bc\".\n<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input:<\/strong> s = \"cbzxy\"\nOutput:<\/strong> -1\nExplanation:<\/strong> There are no characters that appear twice in s.\n<\/pre>\n\n\n\n
Example 4:<\/strong><\/p>\n\n\n\n
Input:<\/strong> s = \"cabbac\"\nOutput:<\/strong> 4\nExplanation:<\/strong> The optimal substring here is \"abba\". Other non-optimal substrings include \"bb\" and \"\".\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • 1 <= s.length <= 300<\/code><\/li>
  • s<\/code> contains only lowercase English letters.<\/li><\/ul>\n\n\n\n
    Solution: Hashtable<\/strong><\/h2>\n\n\n\n
    Remember the first position each letter occurs.<\/p>\n\n\n\n
    Time complexity: O(n)
    Space complexity: O(26) <\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \nclass Solution {\npublic:\n  int maxLengthBetweenEqualCharacters(string s) {\n    vector first(26, -1);\n    int ans = -1;\n    for (int i = 0; i < s.length(); ++i) {\n      int& p = first[s[i] - 'a'];\n      if (p != -1) {\n        ans = max(ans, i - p - 1);\n      } else {\n        p = i;\n      }      \n    }\n    return ans;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    Given a string s, return the length of the longest substring between two equal characters, excluding the two characters. If there is no such substring return -1. A substring is a…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[70],"tags":[222,82,4],"class_list":["post-7525","post","type-post","status-publish","format-standard","hentry","category-hashtable","tag-easy","tag-hashtable","tag-string","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/7525","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/comments?post=7525"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/7525\/revisions"}],"predecessor-version":[{"id":7527,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/7525\/revisions\/7527"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=7525"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=7525"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=7525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}