swift solution with well explanation
IntuitionThe goal is to find the largest outlier in an array. An outlier, in this context, is an element that deviates significantly from the rest of the elemen
# Intuition

The goal is to find the largest outlier in an array. An outlier, in this context, is an element that deviates significantly from the rest of the elements in the array. Instead of using the mean or median, this method identifies an outlier based on a mathematical relationship derived from the sum of the elements and their counts.

# Approach

1.  **Calculate the Total Sum of the Array**: This helps in deriving potential outliers using a mathematical relationship.

2.  **Count Occurrences of Each Number**: A dictionary (or hashmap) is used to keep track of the frequency of each element in the array.

3.  **Identify Potential Outliers**: For each unique number in the array, compute a potential outlier using the formula: `total_sum - 2 * num`. This formula identifies a number that would balance out the total sum if the number `num` was removed.

4.  **Check for Valid Outliers**: Check if the calculated potential outlier exists in the dictionary and ensure that it is a valid outlier (either it is not the same as `num` or it appears more than once).

5.  **Track the Largest Outlier**: Keep track of the largest outlier found during the traversal of the dictionary keys.

# Complexity
- Time complexity: O(n), where n is the number of elements in the array. We traverse the array twice: once to count occurrences and once to identify outliers.

- Space complexity: O(n), due to the storage needed for the dictionary.

# Code
```swift []
class Solution {
    func getLargestOutlier(_ nums: [Int]) -> Int {
        // Step 1: Calculate the total sum of the array
        let totalSum = nums.reduce(0, +)
        
        // Step 2: Create a dictionary to count the occurrences of each number
        var numCounts = [Int: Int]()
        for num in nums {
            numCounts[num, default: 0] += 1
        }
        
        // Step 3: Initialize the largest outlier to negative infinity
        var largestOutlier = Int.min
        
        // Step 4: Traverse the dictionary keys to find the largest outlier
        for num in numCounts.keys {
            let potentialOutlier = totalSum - 2 * num
            
            if let count = numCounts[potentialOutlier], (potentialOutlier != num || numCounts[num]! > 1) {
                largestOutlier = max(largestOutlier, potentialOutlier)
            }
        }
        
        // Step 5: Return the largest outlier
        return largestOutlier
    }
}

```
['Swift']