TrueSkill [1] is a widely accepted algorithm for matchmaking, in which player skills are initialized with a random variable following Gaussian distribution and then get updated through team-based match outcomes. Eventually, with sufficient amount of matches, player skill random variables will converge to some means with very small variance. There are multiple open sourced libraries …
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In this post, I am summarizing all I know for optimization. It is a hard, primary problem once you define your model with some kind of objective function integrating a bunch of parameters and you start to wonder how you could learn the values of those parameters to minimize (or maximize) the objective function. Unconstrained Optimization …
https://leetcode.com/problems/happy-number/ Write an algorithm to determine if a number is “happy”. A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops …
https://leetcode.com/problems/reorder-list/ Given a singly linked list L: L0→L1→…→Ln-1→Ln,reorder it to: L0→Ln→L1→Ln-1→L2→Ln-2→… You must do this in-place without altering the nodes’ values. For example,Given {1,2,3,4}, reorder it to {1,4,2,3}. Code # Definition for singly-linked list. # class ListNode(object): # def __init__(self, x): # self.val = x # self.next = None class Solution(object): def reorderList(self, head): …
https://leetcode.com/problems/fraction-to-recurring-decimal/ Given two integers representing the numerator and denominator of a fraction, return the fraction in string format. If the fractional part is repeating, enclose the repeating part in parentheses. For example, Given numerator = 1, denominator = 2, return “0.5”. Given numerator = 2, denominator = 1, return “2”. Given numerator = 2, denominator …
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https://leetcode.com/problems/scramble-string/ Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively. Below is one possible representation of s1 = "great": great / \ gr eat / \ / \ g r e at / \ a t To scramble the string, we may choose any …
https://leetcode.com/problems/insertion-sort-list/ Sort a linked list using insertion sort. Code # Definition for singly-linked list. # class ListNode(object): # def __init__(self, x): # self.val = x # self.next = None class Solution(object): def insertionSortList(self, head): “”” :type head: ListNode :rtype: ListNode “”” new_head = ListNode(0) cur = head while cur: isrt = new_head next = …
https://leetcode.com/problems/zigzag-conversion/ The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility) P A H N A P L S I I G Y I R And then read line by line: "PAHNAPLSIIGYIR" Write the …
https://leetcode.com/problems/maximum-gap/ Given an unsorted array, find the maximum difference between the successive elements in its sorted form. Try to solve it in linear time/space. Return 0 if the array contains less than 2 elements. You may assume all elements in the array are non-negative integers and fit in the 32-bit signed integer range. Code …
https://leetcode.com/problems/simplify-path/ Given an absolute path for a file (Unix-style), simplify it. For example,path = "/home/", => "/home"path = "/a/./b/../../c/", => "/c" click to show corner cases. Corner Cases: Did you consider the case where path = "/../"?In this case, you should return "/". Another corner case is the path might contain multiple slashes '/' together, …