Comparison Based vs Non Comparison Based Sorting in DSA Javascript - Build Both Approaches

Comparison Based vs Non Comparison Based Sorting

📖 Scenario: You are working in a small online store. You want to sort the list of product prices to show the cheapest items first. You will learn two ways to sort: one by comparing prices directly, and another by using counting since prices are whole numbers.

🎯 Goal: Build two sorting methods: one using comparison (like bubble sort) and one using counting sort (non-comparison). Then print the sorted prices from both methods.

📋 What You'll Learn

Create an array called prices with exact values: [40, 10, 30, 20, 10]

Create a variable called maxPrice and set it to 40

Write a function called bubbleSort that sorts the prices array using comparison

Write a function called countingSort that sorts the prices array using counting sort and maxPrice

Print the sorted arrays from both bubbleSort and countingSort

💡 Why This Matters

🌍 Real World

Sorting prices helps customers find cheaper products quickly in online stores.

💼 Career

Understanding different sorting methods is important for optimizing software performance in real-world applications.

1

Create the prices array

Create an array called prices with these exact values: [40, 10, 30, 20, 10]

DSA Javascript

// Your code here

Hint

Use const prices = [40, 10, 30, 20, 10]; to create the array.

2

Set the maximum price

Create a variable called maxPrice and set it to 40

DSA Javascript

const prices = [40, 10, 30, 20, 10];
// Your code here

Hint

Use const maxPrice = 40; to store the highest price.

3

Write bubbleSort and countingSort functions

Write a function called bubbleSort that sorts the prices array using comparison. Then write a function called countingSort that sorts the prices array using counting sort and maxPrice

DSA Javascript

const prices = [40, 10, 30, 20, 10];
const maxPrice = 40;

// Your code here

Hint

Use nested loops for bubbleSort. Use a count array for countingSort.

4

Print sorted arrays

Print the sorted arrays from both bubbleSort(prices.slice()) and countingSort(prices, maxPrice)

DSA Javascript

const prices = [40, 10, 30, 20, 10];
const maxPrice = 40;

function bubbleSort(arr) {
    let n = arr.length;
    for (let i = 0; i  arr[j + 1]) {
                let temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
            }
        }
    }
    return arr;
}

function countingSort(arr, max) {
    let count = new Array(max + 1).fill(0);
    for (let i = 0; i  0) {
            sortedArr.push(i);
            count[i]--;
        }
    }
    return sortedArr;
}

// Your code here

Hint

Use console.log(bubbleSort(prices.slice())) and console.log(countingSort(prices, maxPrice)) to print sorted arrays.

Practice

1. Which of the following sorting algorithms is non-comparison based?

easy

A. Heap Sort

B. Merge Sort

C. Quick Sort

D. Counting Sort

Solution

1. Step 1: Understand comparison based sorting

   Comparison based sorting algorithms decide order by comparing elements, like Merge Sort, Quick Sort, and Heap Sort.

2. Step 2: Identify non-comparison based sorting

   Counting Sort uses counting of element frequencies instead of comparisons, so it is non-comparison based.

3. Final Answer:

   Counting Sort -> Option D

4. Quick Check:

   Non-comparison based = Counting Sort [OK]

Hint: Counting Sort uses counts, no element comparisons [OK]

Common Mistakes:

• Confusing Quick Sort as non-comparison
• Thinking Merge Sort is non-comparison
• Assuming Heap Sort is non-comparison

2. Which of the following is the correct syntax to call a non-comparison based sorting function countingSort(arr) in JavaScript?

easy

A. countingSort(arr);

B. countingSort arr;

C. countingSort{arr};

D. countingSort[arr];

Solution

1. Step 1: Recall JavaScript function call syntax

   Functions are called with parentheses enclosing arguments, like func(args).

2. Step 2: Match syntax with options

   Only countingSort(arr); uses correct parentheses syntax for function call.

3. Final Answer:

   countingSort(arr); -> Option A

4. Quick Check:

   Function call syntax = countingSort(arr); [OK]

Hint: Use parentheses () to call functions in JavaScript [OK]

Common Mistakes:

• Using square brackets [] instead of parentheses
• Missing parentheses around arguments
• Using curly braces {} incorrectly

3. What will be the output of the following JavaScript code?

function countingSort(arr) {
  const max = Math.max(...arr);
  const count = new Array(max + 1).fill(0);
  arr.forEach(num => count[num]++);
  let sorted = [];
  count.forEach((c, num) => {
    for (let i = 0; i < c; i++) sorted.push(num);
  });
  return sorted;
}

const arr = [3, 1, 4, 1, 5];
console.log(countingSort(arr));

medium

A. [1, 1, 3, 4, 5]

B. [3, 1, 4, 1, 5]

C. [5, 4, 3, 1, 1]

D. [1, 3, 4, 5]

Solution

1. Step 1: Count frequencies of each number

   Input array is [3,1,4,1,5]. Counting frequencies: 1 appears 2 times, 3 once, 4 once, 5 once.

2. Step 2: Build sorted array from counts

   Using counts, output array is [1,1,3,4,5] in ascending order.

3. Final Answer:

   [1, 1, 3, 4, 5] -> Option A

4. Quick Check:

   Counting Sort output = sorted ascending array [OK]

Hint: Counting Sort outputs sorted array by frequency counts [OK]

Common Mistakes:

• Confusing input and output arrays
• Assuming original order is preserved
• Thinking output is reversed

4. The following code attempts to implement Counting Sort but has a bug. What is the bug?

function countingSort(arr) {
  const max = Math.max(...arr);
  const count = new Array(max).fill(0);
  arr.forEach(num => count[num]++);
  let sorted = [];
  count.forEach((c, num) => {
    for (let i = 0; i < c; i++) sorted.push(num);
  });
  return sorted;
}

medium

A. Should use Math.min instead of Math.max

B. Array count size should be max + 1

C. Should initialize count with zeros

D. Should not use forEach on count array

Solution

1. Step 1: Check count array size

   Count array size is max, but indices go from 0 to max, so size must be max + 1.

2. Step 2: Identify impact of wrong size

   Without max + 1 size, count[max] index is undefined, causing errors or missing counts.

3. Final Answer:

   Array count size should be max + 1 -> Option B

4. Quick Check:

   Count array size = max + 1 [OK]

Hint: Count array size must cover max index + 1 [OK]

Common Mistakes:

• Using max instead of max + 1 for array size
• Confusing max with min
• Ignoring array initialization

5. You have an array of integers ranging from 0 to 1000. Which sorting algorithm is best to sort this array efficiently and why?

hard

A. Quick Sort, because it has average O(n log n) time

B. Merge Sort, because it is stable and uses divide and conquer

C. Counting Sort, because it sorts in O(n + k) where k is range size

D. Heap Sort, because it uses a binary heap structure

Solution

1. Step 1: Analyze input constraints

   Array elements range from 0 to 1000, so range size k = 1001, which is small and fixed.

2. Step 2: Choose sorting algorithm based on range

   Counting Sort runs in O(n + k), which is efficient for small k, better than O(n log n) comparison sorts.

3. Step 3: Confirm Counting Sort suitability

   Counting Sort is non-comparison based and ideal for small integer ranges.

4. Final Answer:

   Counting Sort, because it sorts in O(n + k) where k is range size -> Option C

5. Quick Check:

   Small range + Counting Sort = efficient sorting [OK]

Hint: Use Counting Sort for small integer ranges [OK]

Common Mistakes:

• Choosing Quick Sort ignoring range size
• Assuming Merge Sort is always best
• Not considering non-comparison sorts