Explore fun brain teasers to hone your logic, critical thinking, and problem-solving skills. Gain insights into Go and practice to avoid future mistakes.

go.tar.gz

Go lang

Who knew puzzles could be fun? Puzzles and brain teasers are a great way to practice your critical thinking and improve your logic and problem-solving skills. This course provides a basic understanding of Go. The teasers in this course will help you practice what you already know and help avoid future mistakes.

Go Brain Teasers

# Try it yourself ##
Try running the code below to see the result for yourself.

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	var wg sync.WaitGroup
	for _, n := range []int{3, 1, 2} {
		wg.Add(1)
		go func() {
			defer wg.Done()
			time.Sleep(time.Duration(n) * time.Millisecond)
			fmt.Printf("%d ", n)
		}()
	}
	wg.Wait()
	fmt.Println()
}




# Explanation ##
You probably expected `1 2 3`. Each goroutine sleeps `n` milliseconds and then prints `n`. We use the `wg.Wait()` function to wait until all goroutines are done, and then the program will print a newline.

However, the `n` that each goroutine uses is the same `n` as defined in **line 11**. This is known as **closure**.

By design, this is why goroutines (and deferred functions) are written as function invocation with parameters.

We have two options to solve this bug. The first is to pass `n` as a parameter to the goroutine.


Before We Begin

Puzzles

Wrapping Up

Puzzle 8 Explanation: Closure

Try it yourself

Explanation