Code&Data Insights

Mutually exclusive -> disjoint, two events cannot occur at same time -> NO INTERSECTION Q) Find the probabitliy that all of the events A, B, C occurs if A, B, C are mutually exclusive. => Since A, B, C are mutually exclusive, they have no union. The probability that all the events A, B, C occur is 0. P( ABC | A,B,C mutually exclusive ) -> P(ABC) = 0 Independent -> One does not affect to the othe..

[ Data & Data Science Field ]  Data - traditional / bigData science - BI(Business Intelligence) / Traditional Methods / Machine Learning * Data Collection in TRADITIONAL DATA after gathering the data, its need to take the data pre-processing raw data -> data pre-processing -> processing -> Information Where?: Basic customer data / historical stock price data - Class labeling : / - Data cleansin..

[ MAP ] - (key-value) entries and key should be unique! - can store elements in a way that attempts to speed up the process of locating them, through the utilization of keys - main operations: search | insert | delete - methods : get(k), put(k,v), remove(k), entrySet(), keySet(), values(), size(), isEmpty() - we can efficiently implement a map using an unsorted list [ Hash Functions & Hash Table..

Q) What is CFG? [ CFG - Context Free Grammar ] : Context Free Grammar from CFL(Context-Free Language) Grammar G = (V,T,S,P) V(variables) | T(Terminal symbols) | S(Start variable) | P(Productions of the form: A -> x) * CFL(Context-Free Languages): A language L is context-free if and only if there is a context-free grammar(CFG) G that generates it, L = L(G). * Derivation Tree * Normal Forms for CF..

- an ADT for storing a collection of prioritized elements; the elements are referred to as values. (ADT - Abstract Data Type, this focuses on the behaviour of a data structure rather than on any implementation detail 데이터 구조를 사용해 코드를 구현하는 것보다 데이터구조가 어떻게 작동하는지에 초점을 맞춘 것) - A key can be used to indicate the priority of a value( key: can be used to indicate the priority of a value..

* What is Tree in Data Structure? :  non-linear and an abstract model of a hierarchical data structure. parent-child relation(ex) Organization charts, File Systems, Programming environments * Tree Traversals (1) PreOrder Traversal:  Root - Left - Right Algorithm preOrder(x)          visit(x)          for each child y of x                   preorder(y)  (2) PostOrder Traversal: Left- Right - Root..

Q) I cannot understand how to identify a function with a logN time. - binary search는 주어진 배열을 반으로 나눠 검색하고, 거기서 또 반으로 나누고 검색해서 보통 배열 전체를 하나하나 검색하는 것보다 O(n) 더 조금 걸린다. 이건 뭔가 외우듯이? 알게되고 Time Complexity를 공부하고, 문제를 풀때 뭔가 linear time(O(n)) 이나 o(n^2) 같이 딱 개념이 안 잡혔다. Binary Search Tree 튜토리얼에서 배우고 리뷰하는겸 정리하면서 구글링 하다가 Stack Overflow에서 O(logn)에 대한 설명이 잘 되어있는 것을 찾았다. The most common attributes of the logarith..

What is Hash? (해시란 무엇인가 ) key : value 를 갖는 데이터를 관리하고 유지하는 자료구조 (Data Structure) 중 하나이다. 해시는 배열과 달리 String 타입이나 다른 어떤 데이터형을 기반으로 자료구조를 접근하고 데이터를 관리할 수 있게 해준다. 특히, String을 기반으로 정보를 기록하고 관리해야 할 때 (단순 배열 사용 X) Hash Function : 키 값을 수치( > 0 )로 변환하는 함수 : the method/function performing the conversion is referred to as "hash function" h(x) = x mod N ( for integer keys ) Hash Table : 자료를 해시함수의 결과를 사용해 위치(..