LESSON 400 OF 414 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: tr v4 — Squeeze Repeats (-s) in Rust

Practice

Build a version of the Unix tr -s command. Given a list of lines and a string chars, collapse consecutive runs of any character that appears in chars to a single occurrence. Other characters are unchanged. Return the lines joined by newline characters (\n).

Notes: chars is a non-empty ASCII string whose characters are taken literally (no ranges). Only runs of the same character from chars are collapsed; all other characters, and runs of characters not in chars, stay as they are. Upper and lower case are different characters. Lines may be empty.

Function signature:

fn tr_squeeze(lines: Vec<String>, chars: String) -> String

Example:

Input: lines = ["aaabbb", "abaa"], chars = "a"

Output: "abbb\naba"

When printed:
abbb
aba

Collect every char of chars into a HashSet<char>. Walk each line tracking prev (the last char you kept); skip the current char only if it's in the squeeze set AND equals prev.

The full solution:

impl Solution {
    fn tr_squeeze(lines: Vec<String>, chars: String) -> String {
        let squeeze: HashSet<char> = chars.chars().collect();
        let mut result: Vec<String> = Vec::new();
        for line in &lines {
            let mut out = String::new();
            let mut prev = '\0';
            for ch in line.chars() {
                if squeeze.contains(&ch) && ch == prev {
                    continue;
                }
                out.push(ch);
                prev = ch;
            }
            result.push(out);
        }
        result.join("\n")
    }
}

STEP 1 OF 12

Guided

Ctrl + Enter to check

CLI Tool: tr v4 — Squeeze Repeats (-s) in Rust

Tr V4 in Rust