JuniorTheoryCommon

What does the program print?

package main

import "fmt"

func main() {
    a := []int{10, 20, 30, 40}
    b := a[1:2:2]
    b = append(b, 5)
    b[0] = 1
    fmt.Println(a, b)
}

[10 20 30 40] [1 5]

Expecting [10 1 5 40] for a: the third index caps the capacity of b at 1, so append copies b into a new array and leaves a alone.
Expecting b[0] = 1 to reach a: after append moves b to a new array, the two slices no longer share any element.

JuniorTheoryCommon

package main

import "fmt"

func main() {
    a := []int{10, 20, 30, 40}
    b := a[1:2:2]
    b = append(b, 5)
    b[0] = 1
    fmt.Println(a, b)
}

[10 20 30 40] [1 5]

Expecting [10 1 5 40] for a: the third index caps the capacity of b at 1, so append copies b into a new array and leaves a alone.
Expecting b[0] = 1 to reach a: after append moves b to a new array, the two slices no longer share any element.