Le Quang Duy

   Two City Scheduling Solution There are  2N  people a company is planning to interview. The cost of flying the  i -th person to city  A  is  costs[i][0] , and the cost of flying the  i -th person to city  B  is  costs[i][1] . Return the minimum cost to fly every person to a city such that exactly  N  people arrive in each city. Example 1: Input: [[10,20],[30,200],[400,50],[30,20]] Output: 110 Explanation: The first person goes to city A for a cost of 10. The second person goes to city A for a cost of 30. The third person goes to city B for a cost of 50. The fourth person goes to city B for a cost of 20. The total minimum cost is 10 + 30 + 50 + 20 = 110 to have half the people interviewing in each city. Note: 1 <= costs.length <= 100 It is guaranteed that  costs.length  is even. 1 <= costs[i][0], costs[i][1] <= 1000 If you random chooses, you can't control the best solution. Instead of find the best of minimum value for each, we delet

Delete Node in a Linked List Write a function to delete a node (except the tail) in a singly linked list, given only access to that node. Given linked list -- head = [4,5,1,9], which looks like following: Example 1: Input: head = [4,5,1,9], node = 5 Output: [4,1,9] Explanation: You are given the second node with value 5, the linked list should become 4 -> 1 -> 9 after calling your function. Example 2: Input: head = [4,5,1,9], node = 1 Output: [4,5,9] Explanation: You are given the third node with value 1, the linked list should become 4 -> 5 -> 9 after calling your function. Note: The linked list will have at least two elements. All of the nodes' values will be unique. The given node will not be the tail and it will always be a valid node of the linked list. Do not return anything from your function. In a linked list, you can only accest one node, so, you can't know the node prev before. We alway delete a node in linkedlist

Invert a binary tree. Example: Input: 4 / \ 2 7 / \ / \ 1 3 6 9 Output: 4 / \ 7 2 / \ / \ 9 6 3 1 Trivia: This problem was inspired by  this original tweet  by  Max Howell : Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so f*** off. Simalar swap two poiter a and b, this problem is easy with dfs: Thank you !