题解 | 删除公共字符

#include <iostream>
#include <unordered_set>
#include <string>
using namespace std;

string removeCharacters(const string& s1, const string& s2) {
    unordered_set<char> charsToRemove(s2.begin(), s2.end());
    string result;
    
    for (char c : s1) {
        if (charsToRemove.find(c) == charsToRemove.end()) {
            result += c;  // 只添加不在s2中的字符
        }
    }
    
    return result;
}

int main() {
    string s1, s2;
    getline(cin, s1);
    getline(cin, s2);
    
    cout << removeCharacters(s1, s2) << endl;  // 输出结果
    return 0;
}

import java.util.HashSet;
import java.util.Scanner;

public class Main {
    public static String removeCharacters(String s1, String s2) {
        HashSet<Character> charsToRemove = new HashSet<>();
        for (char c : s2.toCharArray()) {
            charsToRemove.add(c);
        }
        
        StringBuilder result = new StringBuilder();
        for (char c : s1.toCharArray()) {
            if (!charsToRemove.contains(c)) {
                result.append(c);  // 只添加不在s2中的字符
            }
        }
        
        return result.toString();
    }
    
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s1 = sc.nextLine();
        String s2 = sc.nextLine();
        
        System.out.println(removeCharacters(s1, s2));  // 输出结果
        sc.close();
    }
}

def remove_characters(s1, s2):
    # 使用集合提高查找效率
    chars_to_remove = set(s2)
    result = ''.join([char for char in s1 if char not in chars_to_remove])
    return result

if __name__ == "__main__":
    s1 = input().strip()
    s2 = input().strip()
    print(remove_characters(s1, s2))