Swift - Data Types
Given a string
sentence, how can you create a dictionary mapping each unique Character to its count in the string?Given a string sentence, how can you create a dictionary mapping each unique Character to its count in the string?
hard📝 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Understand how to count characters
Mapping each character to 1 and combining duplicates by summing counts creates a frequency dictionary.Step 2: Analyze options
UseDictionary(sentence.map { ($0, 1) }, uniquingKeysWith: +)usesDictionary(_:uniquingKeysWith:)with+to sum counts correctly. Usesentence.reduce(into: [:]) { counts, char in counts[char] = 1 }overwrites counts instead of summing. Options A and D are invalid methods.Final Answer:
Use Dictionary(sentence.map { ($0, 1) }, uniquingKeysWith: +) -> Option DQuick Check:
Use Dictionary with uniquingKeysWith: + to count characters [OK]
Quick Trick: Map chars to 1, then sum duplicates with uniquingKeysWith [OK]
Common Mistakes:
- Overwriting counts instead of summing
- Using non-existent string methods
- Confusing character count with string length
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