{"id":9692,"date":"2022-04-27T22:10:51","date_gmt":"2022-04-28T05:10:51","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=9692"},"modified":"2022-04-28T21:26:51","modified_gmt":"2022-04-29T04:26:51","slug":"leetcode-2251-number-of-flowers-in-full-bloom","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/tree\/leetcode-2251-number-of-flowers-in-full-bloom\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 2251. Number of Flowers in Full Bloom"},"content":{"rendered":"\n

You are given a 0-indexed<\/strong> 2D integer array flowers<\/code>, where flowers[i] = [starti<\/sub>, endi<\/sub>]<\/code> means the ith<\/sup><\/code> flower will be in full bloom<\/strong> from starti<\/sub><\/code> to endi<\/sub><\/code> (inclusive<\/strong>). You are also given a 0-indexed<\/strong> integer array persons<\/code> of size n<\/code>, where persons[i]<\/code> is the time that the ith<\/sup><\/code> person will arrive to see the flowers.<\/p>\n\n\n\n

Return an integer array <\/em>answer<\/code> of size <\/em>n<\/code>, where <\/em>answer[i]<\/code> is the number<\/strong> of flowers that are in full bloom when the <\/em>ith<\/sup><\/code> person arrives.<\/em><\/p>\n\n\n\n

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

\"\"\/<\/figure>\n\n\n\n
Input:<\/strong> flowers = [[1,6],[3,7],[9,12],[4,13]], persons = [2,3,7,11]\nOutput:<\/strong> [1,2,2,2]\nExplanation: <\/strong>The figure above shows the times when the flowers are in full bloom and when the people arrive.\nFor each person, we return the number of flowers in full bloom during their arrival.\n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
\"\"\/<\/figure>\n\n\n\n
Input:<\/strong> flowers = [[1,10],[3,3]], persons = [3,3,2]\nOutput:<\/strong> [2,2,1]\nExplanation:<\/strong> The figure above shows the times when the flowers are in full bloom and when the people arrive.\nFor each person, we return the number of flowers in full bloom during their arrival.\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • 1 <= flowers.length <= 5 * 104<\/sup><\/code><\/li>
  • flowers[i].length == 2<\/code><\/li>
  • 1 <= starti<\/sub> <= endi<\/sub> <= 109<\/sup><\/code><\/li>
  • 1 <= persons.length <= 5 * 104<\/sup><\/code><\/li>
  • 1 <= persons[i] <= 109<\/sup><\/code><\/li><\/ul>\n\n\n\n
    Solution: Prefix Sum + Binary Search<\/strong><\/h2>\n\n\n\n
    Use a treemap to store the counts (ordered by time t), when a flower begins to bloom at start, we increase m[start], when it dies at end, we decrease m[end+1]. prefix_sum[t] indicates the # of blooming flowers at time t.<\/p>\n\n\n\n
    For each people, use binary search to find the latest # of flowers before his arrival.<\/p>\n\n\n\n
    Time complexity: O(nlogn + mlogn)
    Space complexity: O(n)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  vector fullBloomFlowers(vector>& flowers, vector& persons) {\n    map m{{0, 0}};\n    for (const auto& f : flowers)\n      ++m[f[0]], --m[f[1] + 1];    \n    int sum = 0;\n    for (auto& [t, c] : m)\n      c = sum += c;    \n    vector ans;    \n    for (int t : persons)      \n      ans.push_back(prev(m.upper_bound(t))->second);\n    return ans;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    You are given a 0-indexed 2D integer array flowers, where flowers[i] = [starti, endi] means the ith flower will be in full bloom from starti to endi (inclusive). You are also given a 0-indexed integer array persons of size n, where persons[i] is the time…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[45],"tags":[217,104,699],"class_list":["post-9692","post","type-post","status-publish","format-standard","hentry","category-tree","tag-hard","tag-sweep-line","tag-treemap","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9692","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=9692"}],"version-history":[{"count":6,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9692\/revisions"}],"predecessor-version":[{"id":9702,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/9692\/revisions\/9702"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=9692"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=9692"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=9692"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}