開発環境
- macOS Sierra - Apple (OS)
- Emacs (Text Editor)
- JavaScript (プログラミング言語)
- Node.js, Safari(JavaScript エンジン)
- Learning JavaScript [邦訳](参考書籍)
The Art of Computer Programming Volume 1 Fundamental Algorithms Third Edition 日本語版(Donald E. Knuth (著)、青木 孝 (著)、筧 一彦 (著)、鈴木 健一 (著)、長尾 高弘 (著)、有澤 誠 (その他)、和田 英一 (その他)、ドワンゴ)の第1章(基礎概念)、1.2(数学的な基礎)、演習問題5を取り組んでみる。
コード(Emacs)
HTML5
n = <input id="n0" type="number" min="2" step="1" value="100"> <br> <button id="run0">run</button> <button id="clear0">clear</button> <pre id="output0"></pre> <script src="sample5.js"></script>
JavaScript
let input0 = document.querySelector('#n0'), btn0 = document.querySelector('#run0'), btn1 = document.querySelector('#clear0'), pre0 = document.querySelector('#output0'), p = (x) => pre0.textContent += x + '\n'; let primes = [undefined, undefined, true]; let isPrime = (n) => { if (primes[n] === undefined) { for (let i = 2; i <= n / 2; i += 1) { if (n % i === 0) { primes[n] = false; return false; } } } primes[n] = true; return true; }; let isInt = (x) => Math.floor(x) === x; let f = (n) => { for (let i = 2; i <= n; i += 1) { isPrime(i); } let result = ''; for (let i = 2; i <= n; i += 1) { if (isPrime(i)) { console.log(i); let j = 0; for (; isInt(n / i);) { n /= i; j += 1; if (n === 1) { if (j === 1) { result += `${i}`; } else if (j > 1) { result += `${i}^${j}`; } return result; } } if (j === 1) { result += `${i} * `; } else if (j > 1) { result += `${i}^${j} * `; } } } }; let output = () => { let n = parseInt(input0.value, 10); for (let i = 2; i <= n; i += 1) { p(`${i} = ${f(i)}`); } }; btn0.onclick = output; btn1.onclick = () => { pre0.textContent = ''; }; output();n =
2 = 2 3 = 3 4 = 2^2 5 = 5 6 = 2 * 3 7 = 7 8 = 2^3 9 = 3^2 10 = 2 * 5 11 = 11 12 = 2^2 * 3 13 = 13 14 = 2 * 7 15 = 3 * 5 16 = 2^4 17 = 17 18 = 2 * 3^2 19 = 19 20 = 2^2 * 5 21 = 3 * 7 22 = 2 * 11 23 = 23 24 = 2^3 * 3 25 = 5^2 26 = 2 * 13 27 = 3^3 28 = 2^2 * 7 29 = 29 30 = 2 * 3 * 5 31 = 31 32 = 2^5 33 = 3 * 11 34 = 2 * 17 35 = 5 * 7 36 = 2^2 * 3^2 37 = 37 38 = 2 * 19 39 = 3 * 13 40 = 2^3 * 5 41 = 41 42 = 2 * 3 * 7 43 = 43 44 = 2^2 * 11 45 = 3^2 * 5 46 = 2 * 23 47 = 47 48 = 2^4 * 3 49 = 7^2 50 = 2 * 5^2 51 = 3 * 17 52 = 2^2 * 13 53 = 53 54 = 2 * 3^3 55 = 5 * 11 56 = 2^3 * 7 57 = 3 * 19 58 = 2 * 29 59 = 59 60 = 2^2 * 3 * 5 61 = 61 62 = 2 * 31 63 = 3^2 * 7 64 = 2^6 65 = 5 * 13 66 = 2 * 3 * 11 67 = 67 68 = 2^2 * 17 69 = 3 * 23 70 = 2 * 5 * 7 71 = 71 72 = 2^3 * 3^2 73 = 73 74 = 2 * 37 75 = 3 * 5^2 76 = 2^2 * 19 77 = 7 * 11 78 = 2 * 3 * 13 79 = 79 80 = 2^4 * 5 81 = 3^4 82 = 2 * 41 83 = 83 84 = 2^2 * 3 * 7 85 = 5 * 17 86 = 2 * 43 87 = 3 * 29 88 = 2^3 * 11 89 = 89 90 = 2 * 3^2 * 5 91 = 7 * 13 92 = 2^2 * 23 93 = 3 * 31 94 = 2 * 47 95 = 5 * 19 96 = 2^5 * 3 97 = 97 98 = 2 * 7^2 99 = 3^2 * 11 100 = 2^2 * 5^2
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