How should I practice First Unique Letter, Case Insensitive?

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

Is First Unique Letter, Case Insensitive associated with Bloomberg LP?

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

First Unique Letter, Case Insensitive

Bloomberg LP● EasyNEW GRADPHONE SCREEN

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Problem statement

Count only English letters in text, treating uppercase and lowercase forms as the same letter. Return the first original one-character spelling whose case-folded letter occurs exactly once.

Ignore all digits and special characters. Return the empty string if no qualifying letter exists.

Function

firstUniqueLetter(text: String) → String

Examples

Example 1

text = "A1a!B?cB"return = "c"

A/a and B/B repeat after case folding; c is unique.

Constraints

0 <= text.length <= 10^5.