LESSON 392 OF 414 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: uniq v4 — Loners Only in Rust

Practice

Build a version of the Unix uniq -u command. Given a list of lines, output only the values whose adjacent run length is exactly one — i.e. lines that did NOT repeat back-to-back. Surviving values are joined by \n.

Function signature:

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

Example:

Input: lines = ["a", "a", "b", "c", "c", "c"]

Output: "b"

When printed:
b

The two "a"s and the three "c"s are dropped because their runs are longer than 1. Only the lone "b" survives.

Track a String named prev and an integer count. When the line changes (or after the loop), flush prev only if count == 1.

if count == 1 {
    result.push(prev.clone());
}

The full solution:

impl Solution {
    fn uniq_once(lines: Vec<String>) -> String {
        let mut result: Vec<String> = Vec::new();
        let mut count = 0;
        let mut prev = String::new();
        for i in 0..lines.len() {
            if count > 0 && lines[i] == prev {
                count += 1;
            } else {
                if count == 1 {
                    result.push(prev.clone());
                }
                prev = lines[i].clone();
                count = 1;
            }
        }
        if count == 1 {
            result.push(prev.clone());
        }
        return result.join("\n");
    }
}

STEP 1 OF 13

Guided

Ctrl + Enter to check

CLI Tool: uniq v4 — Loners Only in Rust

Uniq V4 in Rust