{"id":9929,"date":"2023-02-04T21:25:04","date_gmt":"2023-02-05T05:25:04","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=9929"},"modified":"2023-02-04T21:25:38","modified_gmt":"2023-02-05T05:25:38","slug":"leetcode-2559-count-vowel-strings-in-ranges","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/algorithms\/array\/leetcode-2559-count-vowel-strings-in-ranges\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 2559.\u00a0Count Vowel Strings in Ranges"},"content":{"rendered":"\n

You are given a 0-indexed<\/strong> array of strings words<\/code> and a 2D array of integers queries<\/code>.<\/p>\n\n\n\n

Each query queries[i] = [li<\/sub>, ri<\/sub>]<\/code> asks us to find the number of strings present in the range li<\/sub><\/code> to ri<\/sub><\/code> (both inclusive<\/strong>) of words<\/code> that start and end with a vowel.<\/p>\n\n\n\n

Return an array ans<\/code> of size queries.length<\/code>, where ans[i]<\/code> is the answer to the i<\/code>th<\/sup> query.<\/p>\n\n\n\n

Note<\/strong> that the vowel letters are 'a'<\/code>, 'e'<\/code>, 'i'<\/code>, 'o'<\/code>, and 'u'<\/code>.<\/p>\n\n\n\n

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

Input:<\/strong> words = [\"aba\",\"bcb\",\"ece\",\"aa\",\"e\"], queries = [[0,2],[1,4],[1,1]]\nOutput:<\/strong> [2,3,0]\nExplanation:<\/strong> The strings starting and ending with a vowel are \"aba\", \"ece\", \"aa\" and \"e\".\nThe answer to the query [0,2] is 2 (strings \"aba\" and \"ece\").\nto query [1,4] is 3 (strings \"ece\", \"aa\", \"e\").\nto query [1,1] is 0.\nWe return [2,3,0].\n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> words = [\"a\",\"e\",\"i\"], queries = [[0,2],[0,1],[2,2]]\nOutput:<\/strong> [3,2,1]\nExplanation:<\/strong> Every string satisfies the conditions, so we return [3,2,1].<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • 1 <= words.length <= 105<\/sup><\/code><\/li>
  • 1 <= words[i].length <= 40<\/code><\/li>
  • words[i]<\/code> consists only of lowercase English letters.<\/li>
  • sum(words[i].length) <= 3 * 105<\/sup><\/code><\/li>
  • 1 <= queries.length <= 105<\/sup><\/code><\/li>
  • 0 <= li<\/sub> <= ri<\/sub> < words.length<\/code><\/li><\/ul>\n\n\n\n
    Solution: Prefix Sum<\/strong><\/h2>\n\n\n\n
    Let sum[i] := number of valid strings in words[0:i]<\/p>\n\n\n\n
    For each query [l, r], answer will be sum[r + 1] – sum[l]<\/p>\n\n\n\n
    Time complexity: O(n + q)
    Space complexity: O(n)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  vector vowelStrings(vector& words, vector>& queries) {\n    const size_t n = words.size();\n    vector sum(n + 1);\n    auto check = [](char c) {\n      return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';\n    };\n    for (size_t i = 0; i < n; ++i)\n      sum[i + 1] = sum[i] + \n        (check(words[i][0]) && check(words[i][words[i].size() - 1]));\n    vector ans;\n    for (const auto& q : queries)\n      ans.push_back(sum[q[1] + 1] - sum[q[0]]);\n    return ans;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    You are given a 0-indexed array of strings words and a 2D array of integers queries. Each query queries[i] = [li, ri] asks us to find the number of strings present in…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[184],"tags":[20,200,4,449],"class_list":["post-9929","post","type-post","status-publish","format-standard","hentry","category-array","tag-array","tag-prefix-sum","tag-string","tag-vowel","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9929","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=9929"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9929\/revisions"}],"predecessor-version":[{"id":9931,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9929\/revisions\/9931"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=9929"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=9929"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=9929"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}