Build the next version of the Unix sort command, this time with the -k flag baked in. Each input line is comma-separated and is guaranteed to have at least field fields (a field may be empty, as in "a,,c"). Given a 1-indexed field number, sort the lines stably by the value at that field, compared as strings by character code, and return the original lines joined by newlines (\n). Lines whose fields are equal keep their original relative order. This matches the real command sort -t, -k N,N -s in the C locale. If the list is empty, return the empty string.
Function signature:
func sortLines(lines []string, field int) string
Example:
Input: field = 2, lines = ["alice,30", "bob,25", "carol,40"] Output: "bob,25\nalice,30\ncarol,40" When printed: bob,25 alice,30 carol,40
Use
sort.SliceStable (NOT sort.Slice, which isn't guaranteed stable). Write a helper that extracts the field with strings.Split, compare those keys in the less function, and join the result with strings.Join.
func extractField(line string, field int) string {
parts := strings.Split(line, ",")
return parts[field-1]
}
The full solution:
func extractField(line string, field int) string {
parts := strings.Split(line, ",")
return parts[field-1]
}
func sortLines(lines []string, field int) string {
sortedLines := make([]string, len(lines))
copy(sortedLines, lines)
sort.SliceStable(sortedLines, func(i, j int) bool {
return extractField(sortedLines[i], field) < extractField(sortedLines[j], field)
})
return strings.Join(sortedLines, "\n")
}
Free plan: 30 tutor messages. Premium is unlimited.
Saved
Ctrl + Enter to check
