Build a version of the Unix tr -d command. Given a list of lines and a string chars, remove every character that appears in chars from each line, then return the lines joined by newline characters (\n).
Notes: chars is a non-empty ASCII string whose characters are taken literally (no ranges). Upper and lower case are different characters. A line can become empty after deleting, and then it stays as an empty line in the output.
Function signature:
func trDelete(_ lines: [String], _ chars: String) -> String
Example:
Input: lines = ["banana", "apple"], chars = "aeiou" Output: "bnn\nppl" When printed: bnn ppl
Put each character of
chars into a Set<Character> for O(1) lookup. Walk every line and append characters that are NOT in the set.
The full solution:
class Solution {
func trDelete(_ lines: [String], _ chars: String) -> String {
var set = Set<Character>()
for ch in chars {
set.insert(ch)
}
var result = [String]()
for line in lines {
var out = ""
for ch in line {
if !set.contains(ch) {
out.append(ch)
}
}
result.append(out)
}
return result.joined(separator: "\n")
}
}
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