A stack is a Last In First Out (LIFO) data structure, which means that the last element added to the stack will be the first one to be removed. Think of it as a stack of plates; you can only add (push) or remove (pop) a plate from the top of the stack.
Advantages of Stack:
Simple Structure: Stacks are easy to understand and implement.
Fast Operations: The basic operations (push and pop) are O(1) which means they are very fast.
Memory: As elements are added and removed only from one end, there's no need to resize or shift elements frequently.
Useful for Reversals: They are handy for algorithms which need to reverse data, like backtracking algorithms or undo functionality.
Function Calls: Stacks are used in low-level system processes such as managing function calls (call stack).
Disadvantages of Stack:
Limited Size: In some implementations, the size of the stack might be limited.
Memory Overflow: If we try to push elements onto a stack that's already full, it may result in a stack overflow.
Single-ended Operations: Operations are restricted to one end which can be limiting in some scenarios.
Data Retrieval: Retrieving data not on the top can be cumbersome or slow since you have to pop all the elements above it first.
Exercise
Problem: Implement a simple stack in Go. This stack should have the following methods:
Push - To add an element to the top of the stack.
Pop - To remove and return the top element from the stack.
Peek - To view the top element without removing it.
Solution:
package main
import (
"errors"
"fmt"
)
type Stack []interface{}
func (s *Stack) Push(value interface{}) {
*s = append(*s, value)
}
func (s *Stack) Pop() (interface{}, error) {
if s.IsEmpty() {
return nil, errors.New("stack is empty")
}
length := len(*s)
elem := (*s)[length-1]
*s = (*s)[:length-1]
return elem, nil
}
func (s *Stack) Peek() (interface{}, error) {
if s.IsEmpty() {
return nil, errors.New("stack is empty")
}
return (*s)[len(*s)-1], nil
}
func (s *Stack) IsEmpty() bool {
return len(*s) == 0
}
func main() {
var s Stack
s.Push(1)
s.Push(2)
s.Push(3)
fmt.Println(s) // [1 2 3]
top, _ := s.Peek()
fmt.Println(top) // 3
elem, _ := s.Pop()
fmt.Println(elem) // 3
fmt.Println(s) // [1 2]
}
The above program demonstrates the simple implementation of a stack in Go with basic stack operations.