How to resolve the algorithm Factorial step by step in the D programming language

Published on 12 May 2024 09:40 PM
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How to resolve the algorithm Factorial step by step in the D programming language

Table of Contents

Problem Statement

Write a function to return the factorial of a number. Solutions can be iterative or recursive. Support for trapping negative   n   errors is optional.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Factorial step by step in the D programming language

Source code in the d programming language

uint factorial(in uint n) pure nothrow @nogc
in {
    assert(n <= 12);
} body {
    uint result = 1;
    foreach (immutable i; 1 .. n + 1)
        result *= i;
    return result;
}

// Computed and printed at compile-time.
pragma(msg, 12.factorial);

void main() {
    import std.stdio;

    // Computed and printed at run-time.
    12.factorial.writeln;
}


uint factorial(in uint n) pure nothrow @nogc
in {
    assert(n <= 12);
} body {
    if (n == 0)
        return 1;
    else
        return n * factorial(n - 1);
}

// Computed and printed at compile-time.
pragma(msg, 12.factorial);

void main() {
    import std.stdio;

    // Computed and printed at run-time.
    12.factorial.writeln;
}


import std.stdio, std.algorithm, std.range;

uint factorial(in uint n) pure nothrow @nogc
in {
    assert(n <= 12);
} body {
    return reduce!q{a * b}(1u, iota(1, n + 1));
}

// Computed and printed at compile-time.
pragma(msg, 12.factorial);

void main() {
    // Computed and printed at run-time.
    12.factorial.writeln;
}


uint factorial(in uint n) pure nothrow
in {
    assert(n <= 12);
} body {
    static uint inner(uint n, uint acc) pure nothrow @nogc {
        if (n < 1)
            return acc;
        else
            return inner(n - 1, acc * n);
    }
    return inner(n, 1);
}

// Computed and printed at compile-time.
pragma(msg, 12.factorial);

void main() {
    import std.stdio;

    // Computed and printed at run-time.
    12.factorial.writeln;
}

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