Now build the -n flag of the cat tool, as a new function. It prints every line preceded by its 1-based line number, right-aligned in 6 columns, then a tab character, then the line text. Blank lines are numbered too, and an empty list gives an empty string.
Function signature:
func numberedCat(_ lines: [String]) -> String
Format per line: the line number right-aligned in a field 6 characters wide (padded with spaces on the left), then a literal tab (\t), then the original line.
Example:
Input: lines = ["hello", "world", "foo"]
Output:
" 1\thello\n 2\tworld\n 3\tfoo"
When printed:
1 hello
2 world
3 foo
Build the result in a
String variable. Iterate by index and add a "\n" before every line except the first, then add the formatted line.
String(format: "%6ld", i + 1) right-aligns the number in 6 columns; then add "\t" and lines[i].
The full solution:
class Solution {
func numberedCat(_ lines: [String]) -> String {
var sb = ""
for i in 0..<lines.count {
if i > 0 {
sb += "\n"
}
sb += String(format: "%6ld", i + 1) + "\t" + lines[i]
}
return sb
}
}
Free plan: 30 tutor messages. Premium is unlimited.
Saved
Ctrl + Enter to check
