Question

How to print the first non-repeated character from a string in Swift

Answer 1

import Foundation

func firstNonRepeatedCharacter(in string: String) -> Character? {
    var characterCounts = [Character: Int]()

    for character in string {
        characterCounts[character, default: 0] += 1
    }

    for character in string {
        if characterCounts[character] == 1 {
            return character
        }
    }

    return nil
}

print(firstNonRepeatedCharacter(in: "aaabbcddefg")!) 
print(firstNonRepeatedCharacter(in: "aabbcc") as Any) 
print(firstNonRepeatedCharacter(in: "a")!) 



/*
run:

c
nil
a

*/

 

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