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LESSON 394 OF 414 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: sort v2 — Reverse (Descending) Sort in Rust

Practice

Build the next version of the Unix sort command, this time with the -r flag baked in. Given a list of lines, return them sorted in descending order by character code (the exact reverse of v1's order, like LC_ALL=C sort -r: lowercase letters come before uppercase ones), joined by newline characters (\n). Duplicates are all kept. If the list is empty, return the empty string.

Function signature:

fn sort_lines(lines: Vec<String>) -> String

Example:

Input: lines = ["banana", "apple", "cherry"]

Output: "cherry\nbanana\napple"

When printed:
cherry
banana
apple

Sort with sort_by(|a, b| b.cmp(a)) to reverse the natural ordering, then combine the lines with join("\n").

The full solution:
impl Solution {
    fn sort_lines(lines: Vec<String>) -> String {
        let mut sorted_lines = lines;
        sorted_lines.sort_by(|a, b| b.cmp(a));
        sorted_lines.join("\n")
    }
}

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    Sort V2 in Rust

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