First, we can use priority_queue to deal with that, the time complexity is O(Nlog^k). Since priority_queue is basically a heap, every time we only need to compare the value in O(logk) time, instead of O(n) time. So we need to compare O(Nlog^k) in total. Second is use divid...
Mergeksorted linked lists and return it as one sorted list. Analyze and describe its complexity. 其实这个问题真没有什么“技巧”;想多了反而不好。不外乎就两种方法吧: 1. 各列数量头一个数组成一个数组,然后取其最大者,插入新的数组。 2. 反复调用两个数组合并的函数k-1次 下面是第一种方法,用了...
Runtime:172ms, faster than21.46% of C++ online submissions for Merge k Sorted Lists. Memory Usage:12.8MB, less than5.95% of C++ online submissions for Merge k Sorted Lists. 三、优化措施 上面的实现,之所以性能不足,在于一次归并一个队列,用的是插入排序。其实n路归并,可以用优先级队列priority_queu...
publicclassSolution{publicListNodemergeKLists(List<ListNode> lists){if(lists ==null|| lists.size() ==0) {returnnull; } PriorityQueue<ListNode> q =newPriorityQueue<ListNode> (lists.size(),newComparator<ListNode>() {@Overridepublicintcompare(ListNode a, ListNode b){returnInteger.compare(a.val, b...
* 来源:https://oj.leetcode.com/problems/merge-k-sorted-lists/ * 结果:Time Limit Exceeded * 来源:LeetCode * 博客: ***/ #include <iostream> #include <vector> using namespace std; struct ListNode{ int val; ListNode *next; ListNode(int x):val...
leetcode 23. Merge k Sorted Lists(堆||分治法) 2016-04-18 05:25 −Merge k sorted linked lists and return it as one sorted list. 题意:把k个已经排好序的链表整合到一个链表中,并且这个链表是排了序的。 题解:这是一道经典好题,值得仔细一说。 有两种方法,假设每个链表的平均长... ...
ListNode* mergeKLists(vector<ListNode*>& lists) { ListNode *tmp=new ListNode(-1); ListNode *head=tmp; priority_queue<ListNode*,vector<ListNode*>,cmp> q; for(int i=0;i<lists.size();i++){ if(lists[i]!=nullptr){ q.push(lists[i]); ...
Sorting reverse ordered lists would then take linear time. The case where the number of runs is linear in the input is then quite obscure. For the priority queue based merging in the second phase, we tried two approaches. The first is the classic n-way merge of n sorted runs using our...
Problem 2: Word Search II21. Heap / Priority QueueProblem 1: Merge k Sorted Lists Problem 2: Top K Frequent Elements22. Monotonic StackProblem 1: Daily Temperatures Problem 2: Largest Rectangle in Histogram23. Reservoir SamplingProblem 1: Linked List Random Node Problem 2: Random Pick Index24...
The merge step is the solution to the simple problem of merging two sorted lists(arrays) to build one large sorted list(array). The algorithm maintains three pointers, one for each of the two arrays and one for maintaining the current index of the final sorted array. ...