{"id":5241,"date":"2019-06-22T21:32:35","date_gmt":"2019-06-23T04:32:35","guid":{"rendered":"https:\/\/zxi.mytechroad.com\/blog\/?p=5241"},"modified":"2019-06-26T08:06:41","modified_gmt":"2019-06-26T15:06:41","slug":"leetcode-1094-car-pooling","status":"publish","type":"post","link":"https:\/\/zxi.mytechroad.com\/blog\/heap\/leetcode-1094-car-pooling\/","title":{"rendered":"\u82b1\u82b1\u9171 LeetCode 1094. Car Pooling"},"content":{"rendered":"\n

You are driving a vehicle that has capacity<\/code> empty seats initially available for passengers.  The vehicle only<\/strong> drives east (ie. it cannot<\/strong> turn around and drive west.)<\/p>\n\n\n\n

Given a list of trips<\/code>, trip[i] = [num_passengers, start_location, end_location]<\/code> contains information about the i<\/code>-th trip: the number of passengers that must be picked up, and the locations to pick them up and drop them off.  The locations are given as the number of kilometers due east from your vehicle’s initial location.<\/p>\n\n\n\n

Return true<\/code> if and only if it is possible to pick up and drop off all passengers for all the given trips. <\/p>\n\n\n\n

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

Input: <\/strong>trips = [[2,1,5],[3,3,7]], capacity = 4\nOutput: <\/strong>false\n<\/pre>\n\n\n\n
Example 2:<\/strong><\/p>\n\n\n\n
Input: <\/strong>trips = [[2,1,5],[3,3,7]], capacity = 5\nOutput: <\/strong>true\n<\/pre>\n\n\n\n
Example 3:<\/strong><\/p>\n\n\n\n
Input: <\/strong>trips = [[2,1,5],[3,5,7]], capacity = 3\nOutput: <\/strong>true\n<\/pre>\n\n\n\n
Example 4:<\/strong><\/p>\n\n\n\n
Input: <\/strong>trips = [[3,2,7],[3,7,9],[8,3,9]], capacity = 11\nOutput: <\/strong>true<\/pre>\n\n\n\n
Solution1: Min heap<\/strong><\/h2>\n\n\n\n
Sort events by location<\/p>\n\n\n\n
Time complexity: O(nlogn)
Space complexity: O(n)<\/p>\n\n\n\n
\n
C++<\/h2>\n
\n\n
\n\/\/ Author: Huahua\nclass Solution {\npublic:\n  bool carPooling(vector>& trips, int capacity) {\n    priority_queue q;\n    for (const auto& trip : trips) {\n      int pick_up = -((trip[1] << 10) | (1 << 9) | trip[0]);\n      int drop_off = -((trip[2] << 10) | trip[0]);\n      q.push(pick_up);\n      q.push(drop_off);\n    }\n    while (q.size()) {\n      int key = -q.top(); q.pop();\n      int sign = ((key >> 9) & 1) ? 1: -1;\n      int num = key & 0xFF;\n      if ((capacity -= sign * num) < 0)\n        return false;\n    }\n    return true;\n  }\n};\n<\/pre>\n<\/div><\/div>\n\n\n\n
Solution 2: Preprocessing<\/strong><\/h2>\n\n\n\n
Time complexity: O(n)
Space complexity: O(1000)<\/p>\n\n\n\n
\n
C++<\/h2>\n
\n\n
\n\/\/ Author: Huahua\nclass Solution {\npublic:\n  bool carPooling(vector>& trips, int capacity) {\n    vector d(1001);\n    for (const auto& trip : trips) {\n      d[trip[1]] -= trip[0];\n      d[trip[2]] += trip[0];\n    }\n    for (const int c : d) \n      if ((capacity += c) < 0) return false;\n    return true;\n  }\n};\n<\/pre>\n<\/div><\/div>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
You are driving a vehicle that has capacity empty seats initially available for passengers.  The vehicle only drives east (ie. it cannot turn around and drive west.) Given a list of trips, trip[i] =…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[71],"tags":[73,177],"class_list":["post-5241","post","type-post","status-publish","format-standard","hentry","category-heap","tag-heap","tag-medium","entry","simple"],"_links":{"self":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/5241","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=5241"}],"version-history":[{"count":3,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/5241\/revisions"}],"predecessor-version":[{"id":5260,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/posts\/5241\/revisions\/5260"}],"wp:attachment":[{"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/media?parent=5241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/categories?post=5241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zxi.mytechroad.com\/blog\/wp-json\/wp\/v2\/tags?post=5241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}