{"id":6533,"date":"2020-03-22T13:34:07","date_gmt":"2020-03-22T20:34:07","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=6533"},"modified":"2020-03-22T13:54:42","modified_gmt":"2020-03-22T20:54:42","slug":"leetcode-1386-cinema-seat-allocation","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/hashtable\/leetcode-1386-cinema-seat-allocation\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1386. Cinema Seat Allocation"},"content":{"rendered":"\n
\"\"\/<\/figure>\n\n\n\n

A cinema has n<\/code> rows of seats, numbered from 1 to n<\/code> and there are ten seats in each row, labelled from 1 to 10 as shown in the figure above.<\/p>\n\n\n\n

Given the array reservedSeats<\/code> containing the numbers of seats already reserved, for example, reservedSeats[i]=[3,8]<\/code> means the seat located in row 3<\/strong> and labelled with 8<\/strong> is already reserved. <\/p>\n\n\n\n

Return the maximum number of four-person families you can allocate on the cinema seats.<\/em> A four-person family occupies fours seats in one row<\/strong>, that are next to each other<\/strong>. Seats across an aisle (such as [3,3] and [3,4]) are not considered to be next to each other, however, It is permissible for the four-person family to be separated by an aisle, but in that case, exactly two people<\/strong> have to sit on each side of the aisle.<\/p>\n\n\n\n

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

\"\"\/<\/figure>\n\n\n\n
Input:<\/strong> n = 3, reservedSeats = [[1,2],[1,3],[1,8],[2,6],[3,1],[3,10]]\nOutput:<\/strong> 4\nExplanation:<\/strong> The figure above shows the optimal allocation for four families, where seats mark with blue are already reserved and contiguous seats mark with orange are for one family. \n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 2, reservedSeats = [[2,1],[1,8],[2,6]]\nOutput:<\/strong> 2\n<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input:<\/strong> n = 4, reservedSeats = [[4,3],[1,4],[4,6],[1,7]]\nOutput:<\/strong> 4\n<\/pre>\n\n\n\n
Constraints:<\/strong><\/p>\n\n\n\n
  • 1 <= n <= 10^9<\/code><\/li>
  • 1 <= reservedSeats.length <= min(10*n, 10^4)<\/code><\/li>
  • reservedSeats[i].length == 2<\/code><\/li>
  • 1 <= reservedSeats[i][0] <= n<\/code><\/li>
  • 1 <= reservedSeats[i][1] <= 10<\/code><\/li>
  • All reservedSeats[i]<\/code> are distinct.<\/li><\/ul>\n\n\n\n
    Solution: HashTable + Greedy<\/strong><\/h2>\n\n\n\n
    if both seat[2~5] seat[6~9] are empty, seat two groups.
    if any of seat[2~5] seat[4~7] seat[6~9] is empty seat one group.
    if there is no one sit in a row, seat two groups.<\/p>\n\n\n\n
    Time complexity: O(|reservedSeats|)
    Space complexity: O(|rows|)<\/p>\n\n\n\n
    \n
    C++<\/h2>\n
    \n\n
    \n\/\/ Author: Huahua\nclass Solution {\npublic:\n  int maxNumberOfFamilies(int n, vector>& reservedSeats) {\n    unordered_map rows;\n    for (auto& seat : reservedSeats)\n      rows[seat[0]] |= 1 << (seat[1] - 1);\n    \n    int ans = (n - rows.size()) * 2;\n    \n    for (const auto& [idx, row] : rows) {\n      int s2 = row & 0b0000011110;\n      int s4 = row & 0b0001111000;\n      int s6 = row & 0b0111100000;\n      if (s2 == 0 && s6 == 0)\n        ans += 2;\n      else if (s2 == 0 || s4 == 0 || s6 == 0)\n        ans += 1;\n    }\n    \n    return ans;\n  }\n};\n<\/pre>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"
    A cinema has n rows of seats, numbered from 1 to n and there are ten seats in each row, labelled from 1 to 10 as shown in the figure above. Given the…<\/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":[549,16,284,88,82],"class_list":["post-6533","post","type-post","status-publish","format-standard","hentry","category-hashtable","tag-binary-mask","tag-bit","tag-geometry","tag-greedy","tag-hashtable","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6533","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=6533"}],"version-history":[{"count":2,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6533\/revisions"}],"predecessor-version":[{"id":6538,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/6533\/revisions\/6538"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=6533"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=6533"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=6533"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}