remove_chars.cpp

/**
 * Write an efficient function that deletes characters from an ASCII string. Use
 * the prototype
 * string removeChars( string str, string remove );
 * where any character existing in remove must be deleted from str.
 * For example, given a str of "Battle of the Vowels: Hawaii vs. Grozny"
 * and a remove of "aeiou", the function should transform str to
 * "Bttl f th Vwls: Hw vs. Grzny".
 */

#include "remove_chars.hpp"

#include <set>

void remove_chars(std::string& s, const std::vector<char>& to_remove) {
    std::set<char> chars_to_remove(to_remove.cbegin(), to_remove.cend());
    size_t removed_count = 0;
    for (size_t i = 0; i < s.length(); ++i) {
        if (chars_to_remove.find(s[i]) != chars_to_remove.end()) {
            removed_count++;
            continue;
        }
        s[i - removed_count] = s[i];
    }
    s.resize(s.length() - removed_count);
}