How should I practice First Non-Repeated Character?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Dell Technologies phone screen problems in FastPrep.

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FastPrep tags this as a Dell Technologies phone screen coding practice problem when the problem catalog has that company and stage context.

First Non-Repeated Character

Dell Technologies● EasyFULLTIMEPHONE SCREEN

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Problem statement

Given a string s, return the first character whose total frequency in the complete string is exactly one.

Character comparison is case-sensitive. Return the empty string when no character occurs exactly once.

Function

firstNonRepeatedCharacter(s: String) → String

Examples

Example 1

s = "swiss"return = "w"

The first s repeats, while w appears once and is encountered before i.

Example 2

s = "aabbcc"return = ""

Every character repeats, so there is no qualifying result.

Constraints

0 <= s.length <= 10^5.
Every character is printable ASCII.