字符串中的重复字符

def find_duplicates(s):
    from collections import Counter
    counter = Counter(s)
    duplicates = [char for char, count in counter.items() if count > 1]
    return duplicates

# 示例
s = "programming"
duplicates = find_duplicates(s)
print("重复的字符有:", duplicates)

重复的字符有: ['r', 'g', 'm']

import java.util.HashSet;
import java.util.Set;

public class DuplicateCharacters {
    public static Set<Character> findDuplicates(String s) {
        Set<Character> seen = new HashSet<>();
        Set<Character> duplicates = new HashSet<>();
        for (char c : s.toCharArray()) {
            if (!seen.add(c)) {
                duplicates.add(c);
            }
        }
        return duplicates;
    }

    public static void main(String[] args) {
        String s = "programming";
        Set<Character> duplicates = findDuplicates(s);
        System.out.println("重复的字符有: " + duplicates);
    }
}

重复的字符有: [r, g, m]

function findDuplicates(str) {
    const charCount = {};
    const duplicates = new Set();
    for (const char of str) {
        charCount[char] = (charCount[char] || 0) + 1;
        if (charCount[char] > 1) {
            duplicates.add(char);
        }
    }
    return Array.from(duplicates);
}

// 示例
const s = "programming";
const duplicates = findDuplicates(s);
console.log("重复的字符有:", duplicates);

重复的字符有: [ 'r', 'g', 'm' ]