HashTree红黑树搞定
import java.util.*; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); while(in.hasNextLine()){ String s=in.nextLine(); solve(s); } } public static void solve(String s){ char[] str = s.toCharArray(); Map<Character,Integer> map = new TreeMap<>(); for(char i:str){ if(!map.containsKey(i)){ map.put(i,1); }else{ int value = map.get(i); map.put(i,value+1); } } for(Map.Entry<Character,Integer> entry : map.entrySet()){ System.out.print(entry.getKey()); System.out.print(entry.getValue()); } } }