LESSON 398 OF 413 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: tr v3 — Delete Chars (-d) in C#

Practice

Build a version of the Unix tr -d command. Given a list of lines and a string chars, remove every character that appears in chars from each line, then return the lines joined by newline characters (\n).

Notes: chars is a non-empty ASCII string whose characters are taken literally (no ranges). Upper and lower case are different characters. A line can become empty after deleting, and then it stays as an empty line in the output.

Function signature:

public string TrDelete(List<string> lines, string chars)

Example:

Input: lines = ["banana", "apple"], chars = "aeiou"

Output: "bnn\nppl"

When printed:
bnn
ppl

Put each character of chars into a HashSet<char> for O(1) lookup. Walk every line and append characters that are NOT in the set.

The full solution:

class Solution {
    public string TrDelete(List<string> lines, string chars) {
        HashSet<char> set = new HashSet<char>();
        for (int i = 0; i < chars.Length; i++) {
            set.Add(chars[i]);
        }
        List<string> result = new List<string>();
        foreach (string line in lines) {
            StringBuilder sb = new StringBuilder();
            for (int j = 0; j < line.Length; j++) {
                char ch = line[j];
                if (!set.Contains(ch)) {
                    sb.Append(ch);
                }
            }
            result.Add(sb.ToString());
        }
        return string.Join("\n", result);
    }
}

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CLI Tool: tr v3 — Delete Chars (-d) in C#

Tr V3 in C#