Queue Enqueue/Dequeue

Algorithm

The replay uses the same three values in every language, so this Go DSA implementation can be compared directly with the rest of the DSA track.

front The front is the oldest value still waiting in the queue.

FIFO A queue removes values in first-in, first-out order.

Visual walkthrough

The queue keeps the oldest value at the front and adds new values at the back.

Step 1 - Enqueue 10, 20, 30

New values join at the back. The oldest value, 10, stays at the front.

Step 2 - Dequeue removes 10

Removing from the front returns 10 and makes 20 the new front.

Basic Implementation

                            basic.go
                        

                            package main

import (
	"fmt"
	"strings"
)

func render(values []int) string {
	parts := make([]string, 0, len(values))
	for _, value := range values {
		parts = append(parts, fmt.Sprint(value))
	}
	return strings.Join(parts, " -> ")
}

func main() {
	queue := []int{}
	for _, value := range []int{10, 20, 30} { queue = append(queue, value) }
	removed := []int{}
	for len(queue) > 0 { removed = append(removed, queue[0]); queue = queue[1:] }
	fmt.Println(render(removed))
}

                        

Complexity

Time: O(1) per operation with a real queue
Space: O(n)

Implementation notes

Go starts with queue := []int{} and appends 10, 20, and 30; append may grow the backing array, but the visible queue state becomes [10, 20, 30].
Dequeue reads the front slot with queue[0], appends that value to removed, then advances the slice header with queue = queue[1:].
The loop guard len(queue) > 0 prevents an empty-slice index. Because reslicing keeps a view of the same backing array, a long-lived queue could retain dequeued storage; this tiny replay drains it immediately.
The trace records the empty queue, the enqueue batch, one front removal to removed=[10] with queue=[20, 30], then the remaining removals to removed=[10, 20, 30] and queue=[].
render allocates a []string, converts each int with fmt.Sprint, joins with strings.Join(parts, " -> "), and fmt.Println prints 10 -> 20 -> 30.