简单的字符串-题解(Java代码)

用HashMap，把字符串分割成字符，当作key值put进HashMap中，其value值加1
最后遍历即可

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int len = sc.nextInt();
        for (int i = 0; i < len; i++) {
            System.out.println(f(sc.next()));
        }
    }
    public static String f(String str) {
        String result = "";
        HashMap<Character,Integer> hs = new HashMap<Character,Integer>();
        hs.put(str.charAt(0),1);
        int num = 0;
        for (int i = 1; i < str.length(); i++) {
            if (hs.containsKey(str.charAt(i))) {
                num = hs.get(str.charAt(i)) + 1;
                hs.put(str.charAt(i),num);
            }else {
                hs.put(str.charAt(i),1);
            }
        }
        for(Object key : hs.keySet()) {
            result += (hs.get(key) == 1 ? "" : hs.get(key)) + "" + key;
        }
        return result;
    }
}