Build a tiny version of the Unix grep command. Given a list of lines and a search pattern, return all lines that contain pattern as a substring (case-sensitive), joined by newline characters (\n).
Function signature:
func grep(_ lines: [String], _ pattern: String) -> String
Example:
Input: pattern = "err" lines = ["error: foo", "warning", "another error", "ok"] Output: "error: foo\nanother error" When printed: error: foo another error
If no lines match, return the empty string "".
Note: real grep treats the pattern as a regular expression by default (grep -F matches plain text). Here the pattern is always plain text: just look for it literally, so characters such as . or * mean nothing special.
Iterate over the lines, keep the ones where
line.contains(pattern) is true, then return result.joined(separator: "\n").
The full solution:
class Solution {
func grep(_ lines: [String], _ pattern: String) -> String {
var result = [String]()
for line in lines {
if line.contains(pattern) {
result.append(line)
}
}
return result.joined(separator: "\n")
}
}
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