leetcode-49-group-anagrams.swift

/**

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https://leetcode.com/problems/group-anagrams/


Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

*/

/**
Big O Annotation
Time complexity O(n^2 log n) where n is the amount of elements in nums.
Because we are sorting each string within the loop.
Space complexity O(n) where n is the amount of elements in nums.
*/
func groupAnagrams(_ strs: [String]) -> [[String]] {
        
    /**
    We want to get a map.
    The idea is to get a sorted string
    as the base. And then all uses of that string.

    So example:

    [
        "aet": ["ate","eat","tea"],
        "ant": ["nat","tan"],
        "abt": ["bat"]
    ]
    */
    var anagrams: [String: [String]] = [:]
    
    // Iterate through the string
    for string in strs {
        
        // Get the character sorted version
        let sorted: [Character] = Array(string).sorted()

        // And append it's current string of strs
        anagrams[String(sorted), default: []].append(string)
    }
    
    // Now let's init a result array
    var result: [[String]] = []
    
    // And simply append every [String] value
    for (key, value) in anagrams {
        result.append(value)
    }
    
    return result
}