Swift Coding Test Course, Insertion Sort

Coding tests have become an essential process for software developers today. The ability to solve various algorithmic problems plays a crucial role in real software development tasks. In this course, we will take a deep dive into the ‘Insertion Sort’ algorithm and learn how to implement it in the Swift language. Insertion sort is a simple yet very useful sorting algorithm, which we will cover in detail starting from the basic concepts to actual problem-solving processes.

1. What is Insertion Sort?

Insertion sort is one of the algorithms used to sort a given array, where each element determines its position through iteration and sorts itself accordingly. This algorithm can be likened to sorting cards in a card game. Each card goes to the position that requires sorting, and through this, a sorted array is formed.

2. Basic Principle of Insertion Sort

Insertion sort operates through the following steps:

  1. Starting from the second element, each element is compared to the elements before it at its current position.
  2. If the current element is smaller than the previous element, the current element is moved backward.
  3. This process is repeated until the current element reaches its appropriate position.
  4. The process continues until all elements have been checked.

3. Time Complexity of Insertion Sort

The average and worst-case time complexity of insertion sort is O(n²). This means that as the amount of data increases, performance can degrade. However, it operates quickly at O(n) for sorted or nearly sorted data. In terms of memory usage, insertion sort is not inefficient, with a space complexity of O(1).

4. Implementing Insertion Sort in Swift

Now, let’s actually implement insertion sort in Swift. Below is the code that implements the insertion sort algorithm:


func insertionSort(array: inout [Int]) {
    for i in 1..= 0 && array[j] > key {
            array[j + 1] = array[j]
            j -= 1
        }
        array[j + 1] = key
    }
}

var numbers = [5, 3, 1, 4, 2]
insertionSort(array: &numbers)
print(numbers) // Output: [1, 2, 3, 4, 5]

5. Algorithm Problem: Finding Maximum Profit Using Insertion Sort

Problem: Sort a given integer array using insertion sort and find the maximum difference between two adjacent elements based on the sorted array. This problem can be solved by sorting the array first and then finding the maximum value among the differences of each element and its adjacent elements.

Problem Solving Process

  1. First, sort the array using insertion sort.
  2. Traverse the sorted array and calculate the differences between adjacent elements.
  3. Find the maximum value among the calculated differences.

Swift Implementation Code


func maxAdjacentDifference(array: inout [Int]) -> Int? {
    // Sort the array
    insertionSort(array: &array)
    
    var maxDifference = 0
    for i in 0.. maxDifference {
            maxDifference = difference
        }
    }
    return maxDifference
}

// Test the function with an example
var testArray = [3, 5, 1, 9, 2]
if let maxDiff = maxAdjacentDifference(array: &testArray) {
    print("The maximum difference is: \(maxDiff)")
} else {
    print("The array is empty.")
}

6. Practical Applications

Insertion sort can be applied to various problems due to its simplicity. For example, it is useful for finding data that meets specific conditions or for real-time data processing. It performs well when the rate of data updates is fast and when most of the inserted data is already sorted. Therefore, when adding data in real-time, insertion sort may be suitable without the need for complicated sorting algorithms.

7. Conclusion

In this article, we learned about the insertion sort algorithm and solved the problem of finding the maximum adjacent difference in an array through it. Insertion sort is easy to understand and has concise code, making it suitable for foundational algorithm learning. It will greatly help in laying the groundwork for data structures and algorithms that frequently appear in actual coding tests. In the next course, we will cover more complex sorting algorithms.

If you have any questions or need further information, please leave a comment. Thank you!