Unlock Hidden Code Gems: Shuffle, Sleep Sort, AI One‑Liner & Fast Inverse Square Root

Project address: https://github.com/kelseyhightower/nocode – a GitHub project with 34k stars that claims to provide a lightweight, cross‑platform, fully automated tool that requires no code to deploy, compile, package, install, and run.

Shuffle Algorithm

This two‑line algorithm generates a uniformly random permutation of n elements, equivalent to Java's Collections.shuffle() implementation.

for(int i = n - 1; i >= 0; i--) {
    // rand(0, i) generates a random integer in [0, i]
    swap(arr[i], arr[rand(0, i)]);
}

Sleep Sort

The sleep‑sort technique creates n threads, each associated with one of the n numbers. Each thread sleeps for a duration proportional to its number, then prints the number when it wakes, resulting in a sorted output.

public class SleepSort {
    public static void main(String[] args) {
        int[] ints = {1,4,7,3,8,9,2,6,5};
        SortThread[] sortThreads = new SortThread[ints.length];
        for(int i = 0; i < sortThreads.length; i++) {
            sortThreads[i] = new SortThread(ints[i]);
        }
        for(int i = 0; i < sortThreads.length; i++) {
            sortThreads[i].start();
        }
    }
}

class SortThread extends Thread {
    int ms = 0;
    public SortThread(int ms) { this.ms = ms; }
    public void run() {
        try {
            sleep(ms * 10 + 10);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(ms);
    }
}

AI Core Code

A minimalist AI‑style loop that reads input, removes Chinese question particles, and prints the transformed string.

while True:
    print(input('').replace('吗','').replace('？','！'))

Get Next Day Time

Simple code to pause execution for one day (86,400 seconds).

// Sleep for one day
thread.sleep(86400*1000L);

0x5f375a86 – Fast Inverse Square Root

This mysterious constant originates from a famous fast inverse square‑root algorithm used in graphics engines. The original magic number is 0x5f3759df; variations like 0x5f37642f and 0x5f375a86 have been discovered through theoretical analysis and brute‑force search.

Hello World

A classic "Hello World" example, included as a reminder that every programmer starts with this simple program regardless of language.