Daily Challenge #206 - Pound Means Backspace

pub fn clean_string(text: &str) -> String { let mut result = String::new(); for ch in text.chars() { if ch == '#' { result.pop(); } else { result.push(ch); } } result } fn main() { assert_eq!(clean_string("abc#de##c"), "abc"); assert_eq!(clean_string("abc####dhh##c#"), "d"); assert_eq!(clean_string("Thee# Empires# SS#tateBuildingg#"), "The Empire StateBuilding"); } 

 def cleanString (str: String): String = { (str.toList.foldLeft(List[Char]()) { case (Nil, '#') => Nil case (x :: xs, '#') => xs case (xs, c) => c :: xs }).reverse.mkString } 

function cleanString(str) { while(str.match(/[^#]#/)) { str = str.split(/[^#]#/).join(''); } str = str.replace(/^#+/, ''); return str; } 

FUNCTION cleanString RETURNS CHARACTER (pcString AS CHARACTER): DEFINE VARIABLE i AS INTEGER NO-UNDO. DEFINE VARIABLE c AS CHARACTER NO-UNDO. DO i = 1 TO LENGTH(pcString): CASE SUBSTRING(pcString,i,1): WHEN '#' THEN IF c > '' THEN c = SUBSTRING(c, 1, LENGTH(c) - 1). OTHERWISE c = c + SUBSTRING(pcString,i,1). END CASE. END. RETURN c. END FUNCTION. MESSAGE cleanString("abc#def##ghi###") = "abd" SKIP cleanString("abc#d##c") = "ac" SKIP cleanString("abc##d######") = "" SKIP cleanString("#######") = "" SKIP cleanString("") = "" VIEW-AS ALERT-BOX INFORMATION BUTTONS OK. 

(defn clean-string [s] (->> (reduce #(if (= \# %2) (pop %1) (conj %1 %2)) '() s) (reverse) (apply str))) 

string cleanString(string s){ string ans = ""; // the answer string int length = 0; // length of answer string for(char c : s){ if(c == '#'){ // if c == '#' and length > 0, then pop one character and decrement length if(length > 0){ ans.pop_back(); length--; } } // else add the character to string and increment length else{ ans += c; length++; } } return ans; } 

cleanString :: String -> String cleanString = reverse . clean 0 . reverse where clean :: Int -> String -> String clean _ "" = "" clean d ('#':rest) = clean (d + 1) rest clean 0 (ch:rest) = ch : clean 0 rest clean d (ch:rest) = clean (d - 1) rest 

/** * Remove backspaces from a string * @param {String} string * @throws {Error} If the function gets called with more or less than one argument * @throws {TypeError} If the function gets called with a non-string argument * @return {String} */ function cleanString(string) { if (arguments.length !== 1) { throw new Error("Expected exactly one argument."); } if (typeof string !== "string") { throw new TypeError("Expected first argument to be a string."); } const characters = []; for (const character of string) { // If this is a character if (character !== "#") { characters.push(character); continue; } // If this is a backspace character // And that there is at least one character  if (characters.length) { characters.pop(); } } return characters.join(""); } 

import re def clean_text(text, _back_hash = re.compile(r'[^#]#')): changes = '#' in text while changes: text, changes = _back_hash.subn('', text) return text.replace('#', '') def tests(): data = ( ("abc#def##ghi###", "abd"), ("abc#d##c", "ac"), ("abc##d######", ""), ("#######", ""), ("", ""), ) for inp, out in data: assert clean_text(inp) == out, \ f"{inp!r} cleaned is not {out!r} but {clean_text(inp)!r}" print('All tests OK!') if __name__ == '__main__': for x in ('abc#de##c', 'abc####dhh##c#', 'Thee# Empires# SS#tateBuildingg#'): print(f"{x!r} ⇒ {clean_text(x)!r}") tests() 

cleanString = lambda s,countPound=0 : ''.join(filter(lambda char : not isinstance(char, int), [(countPound := countPound + 1) if c == '#' else c if countPound == 0 else (countPound := countPound - 1) for c in s[::-1]]))[::-1] print(cleanString("Thee# Empires# SS#tateBuildingg#")) # The Empire StateBuilding print(cleanString("abc#d##c")) # ac print(cleanString("abc#def##ghi###")) # abd print(cleanString("abc##d######")) # empty string print(cleanString("#######")) # empty string print(cleanString("abc#de##c")) # abc print(cleanString("abc####dhh##c#")) # d print(cleanString("abcdef")) # abcdef print(cleanString("########c")) # c 

def cleanString(s): countPound = 0 ans = "" for c in s[::-1]: if c == '#': countPound += 1 else: if countPound == 0: ans += c else: countPound -= 1 return ans[::-1]