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suissa/Combinatoria-suissa-factorial.js

Created January 21, 2022 03:28
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  1. suissa created this gist Jan 21, 2022.
    43 changes: 43 additions & 0 deletions Combinatoria-suissa-factorial.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,43 @@
    function trampoline(f) {
    return function trampolined(...args) {
    let result = f.bind(null, ...args);

    while (typeof result === 'function') result = result();

    return result;
    };
    }

    function _factorial(n) {
    if (n <= 1) return 1;
    return n * _factorial(n - 1);
    }

    const factorial = trampoline(function _factorial(n, acc = 1) {
    if (n <= 1) return acc;
    return () => _factorial(n - 1, n * acc);
    });

    const produtorio = (start, end) =>
    Array
    .from({ length: start - end + 1 }, (v, k) => k + end)
    .reduce((total, n) => total * n , 1)

    const Comb = (n, k) =>
    factorial(n) / (factorial(k) * factorial(n-k))

    const CombSuissa = (n, k) =>
    (k == 2)
    ? (n/k) * (n-1)
    : produtorio(n, n - k + 1) / factorial(k)

    const n = 15
    const k = 3

    console.log(
    Comb(n, k)
    )

    console.log(
    CombSuissa(n, k)
    )