findMedianArray()

Step 1: Understanding the Problem

The task is to find the median of an array of integers. In statistics, the median is the value separating the higher half from the lower half of a data sample. If we sort the array in non-decreasing order, the median is the middle element if the array size is odd, and average of two middle numbers if the size is even.

Here is the initial function declaration:

func findMedian(array: [Int]) -> Double {}

Step 2: Check for Empty Array

Before we proceed, we should handle the case where the input array is empty. In this case, we can return 0.0.

func findMedian(array: [Int]) -> Double {
    if array.isEmpty {
        return 0.0
    }
}

Step 3: Sort the Array

The next step is to sort the array in non-decreasing order. We can use the built-in sort function in Swift.

func findMedian(array: [Int]) -> Double {
    if array.isEmpty {
        return 0.0
    }
    let sortedArray = array.sorted()
}

Step 4: Find the Median

Now, we can find the median based on the length of the sorted array. Remember that array indices start at 0.

func findMedian(array: [Int]) -> Double {
    if array.isEmpty {
        return 0.0
    }
    let sortedArray = array.sorted()
    let middleIndex = sortedArray.count / 2
    if sortedArray.count % 2 == 0 {
        return Double(sortedArray[middleIndex - 1] + sortedArray[middleIndex]) / 2.0
    } else {
        return Double(sortedArray[middleIndex])
    }
}

Conclusion

This function now successfully finds the median of an array in Swift. It handles empty arrays, and works correctly for both even and odd length arrays. The sort function has a time complexity of O(n log n) and finding the median has a time complexity of O(1), so the overall time complexity is O(n log n).