Push Operation on Stack in DSA Go - Build from Scratch

Push Operation on Stack

📖 Scenario: Imagine you are managing a stack of books. You want to add new books on top of the stack one by one.

🎯 Goal: Build a simple stack using a slice in Go and perform push operations to add items on top.

📋 What You'll Learn

Create a stack as a slice of strings with initial books

Create a variable to hold the new book to push

Write code to push the new book onto the stack

Print the stack after the push operation

💡 Why This Matters

🌍 Real World

Stacks are used in many places like undo features in apps, browser history, and managing tasks in order.

💼 Career

Understanding stack operations is important for software development roles that involve data structure manipulation and algorithm design.

1

Create the initial stack

Create a slice of strings called stack with these exact books: "Book1", "Book2", "Book3"

DSA Go

// Create the initial stack slice with books
// Your code here

Hint

Use a slice literal to create stack with the given book names.

2

Add a new book to push

Create a string variable called newBook and set it to "Book4"

DSA Go

package main

import "fmt"

func main() {
    stack := []string{"Book1", "Book2", "Book3"}
    
    // Create newBook variable
    // Your code here
}

Hint

Declare newBook as a string and assign it the value "Book4".

3

Push the new book onto the stack

Use the append function to add newBook to the end of stack and update stack with the result

DSA Go

package main

import "fmt"

func main() {
    stack := []string{"Book1", "Book2", "Book3"}
    newBook := "Book4"
    
    // Push newBook onto stack
    // Your code here
}

Hint

Use stack = append(stack, newBook) to add the new book on top.

4

Print the stack after push

Write a fmt.Println statement to print the stack slice

DSA Go

package main

import "fmt"

func main() {
    stack := []string{"Book1", "Book2", "Book3"}
    newBook := "Book4"
    stack = append(stack, newBook)
    
    // Print the stack
    // Your code here
}

Hint

Use fmt.Println(stack) to display the stack contents.

Practice

1. What does the push operation do in a stack?

easy

A. Returns the bottom element of the stack

B. Removes the top element from the stack

C. Adds an element to the top of the stack

D. Checks if the stack is empty

Solution

1. Step 1: Understand stack behavior

   A stack follows Last In First Out (LIFO) principle, so new elements are added on top.

2. Step 2: Define push operation

   The push operation adds a new element to the top of the stack.

3. Final Answer:

   Adds an element to the top of the stack -> Option C

4. Quick Check:

   Push = Add top [OK]

Hint: Push means add on top of stack [OK]

Common Mistakes:

• Confusing push with pop operation
• Thinking push removes elements
• Assuming push accesses bottom element

2. Which of the following is the correct syntax to push an element 5 onto a stack named s in Go?

easy

A. s.push(5)

B. s.Push(5)

C. push(s, 5)

D. s = append(s, 5)

Solution

1. Step 1: Understand Go slice as stack

   In Go, stacks are often implemented using slices. To push, append adds element at the end.

2. Step 2: Identify correct syntax

   Using append(s, 5) adds 5 to the slice s, simulating push.

3. Final Answer:

   s = append(s, 5) -> Option D

4. Quick Check:

   Go push = append slice [OK]

Hint: Use append to push in Go slices [OK]

Common Mistakes:

• Using lowercase push method which doesn't exist
• Calling push as a function without method
• Ignoring that slices need reassignment after append

3. What will be the output after executing this Go code?

stack := []int{1, 2, 3}
stack = append(stack, 4)
fmt.Println(stack)

medium

A. [1 2 3 4]

B. [4 1 2 3]

C. [1 2 3]

D. runtime error

Solution

1. Step 1: Initial stack state

   Stack slice starts as [1 2 3].

2. Step 2: Append 4 to stack

   Append adds 4 at the end, so stack becomes [1 2 3 4].

3. Final Answer:

   [1 2 3 4] -> Option A

4. Quick Check:

   Append adds at end [OK]

Hint: Append adds element at slice end [OK]

Common Mistakes:

• Expecting append to add at start
• Confusing append with insert
• Thinking append causes error without reassignment

4. Identify the error in this Go code that tries to push an element onto a stack:

var stack []int
stack.push(10)

medium

A. Stack is not initialized

B. push method does not exist for slices

C. Missing import for stack package

D. Cannot push integer 10

Solution

1. Step 1: Check stack type and methods

   Stack is a slice of int. Slices do not have a push method in Go.

2. Step 2: Identify correct push approach

   To push, use append function instead of push method.

3. Final Answer:

   push method does not exist for slices -> Option B

4. Quick Check:

   Slices lack push method [OK]

Hint: Slices use append, no push method [OK]

Common Mistakes:

• Assuming push is built-in method for slices
• Thinking stack must be initialized first
• Believing import fixes method absence

5. Given a stack implemented as a slice in Go, how would you push multiple elements 7, 8, 9 in one operation?

hard

A. stack = append(stack, []int{7, 8, 9}...)

B. stack.push(7); stack.push(8); stack.push(9)

C. append(stack, 7, 8, 9)

D. stack = append(stack, []int{7, 8, 9})

Solution

1. Step 1: Understand appending multiple elements

   To add multiple elements from a slice, use the ... operator to unpack them.

2. Step 2: Identify correct append syntax

   Using append(stack, []int{7, 8, 9}...) adds all three elements individually.

3. Final Answer:

   stack = append(stack, []int{7, 8, 9}...) -> Option A

4. Quick Check:

   Use ... to unpack slice in append [OK]

Hint: Use ... to append multiple elements at once [OK]

Common Mistakes:

• Forgetting to assign the result of append back to stack
• Using non-existent push method multiple times
• Appending slice without unpacking elements