C

I appreciate beautiful, readable code. And if someone were to ask me for an example of beautiful code, I’ve always had the answer ready: the linked list implementation in the Linux kernel.

The code is gorgeous in its simplicity, clarity, and amazing flexibility. If there’s ever a museum for code, this belongs there. It is a masterpiece of the craft.

I was just telling a friend about it while we talked about beautiful code and he found this piece that I share here: Linux Kernel Linked List Explained.

The language can make a brute-force search faster, but eliminating unnecessary work is better. Substituting $c = 1000 - a - b$ into the Pythagorean equation and solving for $b$ leaves only one variable to search:

#include <stdio.h>

int main(void)
{
    const int sum = 1000;

    for (int a = 1; a < sum / 3; ++a) {
        const int numerator = sum * (sum - 2 * a);
        const int denominator = 2 * (sum - a);

        if (numerator % denominator != 0)
            continue;

        const int b = numerator / denominator;
        const int c = sum - a - b;

        if (a < b && b < c) {
            printf("%d %d %d = %d\n", a, b, c, a * b * c);
            return 0;
        }
    }

    fputs("no solution\n", stderr);
    return 1;
}

The divisibility check ensures that b is an integer. This searches fewer than sum / 3 candidates in constant space and prints $200 \times 375 \times 425 = 31\,875\,000$.