코딩 연습

69번 문제는 다음과 같다. Euler's Totient function, φ(n) [sometimes called the phi function], is used to determine the number of numbers less than n which are relatively prime to n. For example, as 1, 2, 4, 5, 7, and 8, are all less than nine and relatively prime to nine, φ(9)=6. n Relatively Prime φ(n) n/φ(n) 2 1 1 2 3 1,2 2 1.5 4 1,3 2 2 5 1,2,3,4 4 1.25 6 1,5 2 3 7 1,2,3,4,5,6 6 1.1666... 8 1,3,5,7 4 2..

68번 문제는 다음과 같다. Consider the following "magic" 3-gon ring, filled with the numbers 1 to 6, and each line adding to nine. Working clockwise, and starting from the group of three with the numerically lowest external node (4,3,2 in this example), each solution can be described uniquely. For example, the above solution can be described by the set: 4,3,2; 6,2,1; 5,1,3. It is possible to complete the ..

67번 문제는 다음과 같다. By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23. 3 7 4 2 4 6 8 5 9 3 That is, 3 + 7 + 4 + 9 = 23. Find the maximum total from top to bottom in triangle.txt (right click and 'Save Link/Target As...'), a 15K text file containing a triangle with one-hundred rows. NOTE: It is not possible to try ..

66번 문제는 다음과 같다. Consider quadratic Diophantine equations of the form: x2 – Dy2 = 1 For example, when D=13, the minimal solution in x is 6492 – 13×1802 = 1. It can be assumed that there are no solutions in positive integers when D is square. By finding minimal solutions in x for D = {2, 3, 5, 6, 7}, we obtain the following: 32 – 2×22 = 1 22 – 3×12 = 1 92 – 5×42 = 1 52 – 6×22 = 1 82 – 7×32 = 1 Hen..

문제는 다음과 같다. Each character on a computer is assigned a unique code and the preferred standard is ASCII (American Standard Code for Information Interchange). For example, uppercase A = 65, asterisk (*) = 42, and lowercase k = 107. A modern encryption method is to take a text file, convert the bytes to ASCII, then XOR each byte with a given value, taken from a secret key. The advantage with the XO..

문제는 다음과 같다. In the card game poker, a hand consists of five cards and are ranked, from lowest to highest, in the following way: High Card: Highest value card.One Pair: Two cards of the same value.Two Pairs: Two different pairs.Three of a Kind: Three cards of the same value.Straight: All cards are consecutive values.Flush: All cards of the same suit.Full House: Three of a kind and a pair.Four of ..

얼마전에 project euler 라는 사이트를 알게 되었고, 프로그래밍 연습도 할 겸 해서 한 문제씩 풀고 있다. 재미있게 여러 가지 연습을 해 볼 수 있어서 좋다고 생각한다. 대부분의 문제가 간단하게 풀리지만 어떤 경우는 오랜 시간 생각을 많이 해야만 풀리는 문제도 있는데, 51번 문제가 그러했다. 프로젝트 오일러 사이트에서 다른 사람들을 위해서 정답을 공개하지는 말라는 당부가 있었기에 여기서는 문제를 풀기 위한 힌트를 제공하려고 한다. 51번 문제는 다음과 같다. By replacing the 1st digit of the 2-digit number *3, it turns out that six of the nine possible values: 13, 23, 43, 53, 73, and 83, a..