2009年05月の記事一覧
- RubyでProject Euler - Problem 10
- Problem 10 (Project Euler) [和訳])
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.Find the sum of all the primes below two million.
さすがに200万までの素数となると、「mathn」のPrimeだと少し遅く感じます。もちろん、「next_prime」も同様。解答...
2009/05/31 - [Ruby]
- RubyでProject Euler - Problem 9
- Problem 9 (Project Euler) [和訳])
A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
a2 + b2 = c2
For example, 32 + 42 = 9 + 16 = 25 = 52.
There exists exactly one Pythagorean triplet for which a + b + c = 1000.
Fi...
2009/05/31 - [Ruby]
- RubyでProject Euler - Problem 8
- Problem 8 (Project Euler) [和訳])
Find the greatest product of five consecutive digits in the 1000-digit number.以下略
なんかどうやっても大差はないようで、解説のPDF文書もありません。
課題の文字列を"split(//)"で配列にしてから、"to_i"で計算しただ...
2009/05/31 - [Ruby]
- RubyでProject Euler - Problem 7
- Problem 7 (Project Euler) [和訳])
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10001st prime number?
件のメソッド「next_prime」では答えにたどり着くのに２分近くかかりました(笑)
...
2009/05/30 - [Ruby]
- RubyでProject Euler - Problem 6
- Problem 6 (Project Euler) [和訳])
The sum of the squares of the first ten natural numbers is,
12 + 22 + ... + 102 = 385
The square of the sum of the first ten natural numbers is,
(1 + 2 + ... + 10)2 = 552 = 3025
Hence the difference between t...
2009/05/30 - [Ruby]
- RubyでProject Euler - Problem 5
- Problem 5 (Project Euler) [和訳])
2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
What is the smallest number that is evenly divisible by all of the numbers from 1 to 20?
電卓を使って...
2009/05/30 - [Ruby]
- RubyでProject Euler - Problem 4
- Problem 4 (Project Euler) [和訳])
A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers.
Ru...
2009/05/29 - [Ruby]
- RubyでProject Euler - Problem 3
- Problem 3 (Project Euler) [和訳])
The prime factors of 13195 are 5, 7, 13 and 29.What is the largest prime factor of the number 600851475143 ?
素因数分解の問題ですから、素数のリストが必要となります。
Rubyに標準で添付されている「mathn」というラ...
2009/05/29 - [Ruby]
- RubyでProject Euler - Problem 2
- Problem 2 (Project Euler) [和訳])
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...Find the sum of all the even-value...
2009/05/28 - [Ruby]
- RubyでProject Euler - Problem 1
- はじめに
ご無沙汰しておりました。
私自身は健康だったのですが、いろいろときついことが重なり、Webから離れてしまった次第です。
さて、気を取り直し、表題の通りやってみます。
Project Euler
既に同様のことを実施されているブログもいくつかありますが、...
2009/05/26 - [Ruby]
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