First and Last Occurrence of Element in DSA Go - Build from Scratch

First and Last Occurrence of Element

📖 Scenario: You are working with a list of product IDs scanned at a store checkout. Some products appear multiple times. You want to find the first and last time a specific product was scanned.

🎯 Goal: Build a Go program that finds the first and last position of a given product ID in a list.

📋 What You'll Learn

Create a slice of integers called products with the exact values: 101, 203, 101, 405, 203, 101

Create an integer variable called target and set it to 101

Write a loop to find the first and last index of target in products

Print the first and last occurrence indices in the format: First: X, Last: Y

💡 Why This Matters

🌍 Real World

Finding first and last occurrences helps in searching logs, tracking events, or analyzing repeated data in real applications.

💼 Career

This skill is useful for software developers working with arrays, slices, or lists to analyze data and implement search features.

1

Create the product list

Create a slice of integers called products with these exact values: 101, 203, 101, 405, 203, 101

DSA Go

// Create the products slice with the given values
// Your code here

Hint

Use products := []int{101, 203, 101, 405, 203, 101} to create the slice.

2

Set the target product ID

Create an integer variable called target and set it to 101

DSA Go

package main

func main() {
    products := []int{101, 203, 101, 405, 203, 101}
    // Create target variable and set to 101
    // Your code here
}

Hint

Use target := 101 to create the variable.

3

Find first and last occurrence

Write a for loop with index i and value p to iterate over products. Inside the loop, find the first and last index of target and store them in variables first and last. Initialize first to -1 before the loop.

DSA Go

package main

func main() {
    products := []int{101, 203, 101, 405, 203, 101}
    target := 101
    first := -1
    // Write a for loop with i, p := range products
    // Update first and last when p == target
    // Your code here
}

Hint

Use for i, p := range products and check if p == target. Set first only once, update last each time.

4

Print the first and last occurrence

Print the first and last occurrence indices using fmt.Printf in this exact format: First: X, Last: Y where X and Y are the values of first and last.

DSA Go

package main

import "fmt"

func main() {
    products := []int{101, 203, 101, 405, 203, 101}
    target := 101
    first := -1
    last := -1
    for i, p := range products {
        if p == target {
            if first == -1 {
                first = i
            }
            last = i
        }
    }
    // Print first and last in format: First: X, Last: Y
    // Your code here
}

Hint

Use fmt.Printf("First: %d, Last: %d\n", first, last) to print the result.