Swift Coding Test Course, Finding Minimum Value 2

Hello, everyone! Today is the second session of our algorithm problem-solving course for employment using Swift. In this session, we will tackle the problem of finding the minimum value within a given array. I will provide detailed explanations to help you develop a foundational mindset for solving algorithm problems, so please pay attention.

Problem Description

We have a given integer array numbers. This array can contain negative and positive numbers, as well as 0. Our goal is to find the minimum value in this array and return the index at which this minimum value is located. If the array is empty, we should return -1. Here are examples of the problem:

Input Format

• Integer array numbers (length: 0 or more)

Output Format

• The index of the minimum value (integer)

Example

Input: numbers = [3, 1, 4, 1, 5, 9, 2, 6, 5]
Output: 1
Explanation: The minimum value is 1, and its index is 1.
    

Input: numbers = []
Output: -1
Explanation: Since the array is empty, we return -1.
    

Problem-Solving Process

Now, let’s take a step-by-step look at the process of solving the problem.

Step 1: Understanding the Problem

First, we need to accurately understand the given problem. We need to find the index of the minimum value in a number array, and note that we should return -1 if the collection is empty. Therefore, the approach will vary depending on the length of the array.

Step 2: Developing a Strategy

The most intuitive way to find the minimum value is to iterate through the array once. During this process, we can update the minimum value while comparing each element and keep track of its position. When the size of the array is n, the time complexity of this approach is O(n). This can be considered an efficient approach.

Step 3: Implementing the Algorithm

Now, let’s implement our algorithm in Swift. Here is the Swift code to find the minimum value:

func findMinIndex(numbers: [Int]) -> Int {
    // Return -1 if the array is empty
    if numbers.isEmpty {
        return -1
    }
    
    var minIndex = 0 // Index of the minimum value
    var minValue = numbers[0] // Minimum value
    
    // Iterate through the array
    for index in 1..
Step 4: Code Explanation
The code above works by iterating through the array, updating the minimum value and its corresponding index.

if numbers.isEmpty: Returns -1 if the array is empty.
var minIndex = 0: Initializes the minimum value index.
var minValue = numbers[0]: Sets the initial minimum value to the first element.
for index in 1..: Iterates through the remaining elements of the array.

if numbers[index] < minValue: Updates the minimum value and index if the current element is less than the minimum value.

Step 5: Test Cases
Now, let’s run various test cases to verify that our implementation is correct. Here are some test cases:
print(findMinIndex(numbers: [3, 1, 4, 1, 5, 9, 2, 6, 5])) // 1
print(findMinIndex(numbers: [])) // -1
print(findMinIndex(numbers: [10, -3, 2, 5])) // 1
print(findMinIndex(numbers: [1, 1, 1, 1])) // 0
print(findMinIndex(numbers: [-10, -20, 0, 5])) // 1
    
Conclusion
Today, we explored the process of implementing an algorithm to find the minimum value in an array using Swift. Such problems frequently appear in various coding tests and can help familiarize you with fundamental arrays and control structures. I hope to continue solving various algorithm problems together to further enhance your coding skills. Thank you!

    Note: Complex algorithm problems can be approached in various ways. Always understand the conditions and requirements of the problem well, and seek efficient methods.




	
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