题解 | #删除字符串中出现次数最少的字符#

感觉步骤比较复杂，有可以优化的地方

public class Main{
	public static void main(String[] args){		Scanner sc = new Scanner(System.in);
		while(sc.hasNext()){
			StringBuffer sb = new StringBuffer();
			Map<Character,Integer> map = new HashMap<>();
			String str = sc.nextLine();
			
			for(int i=0;i<str.length();i++){
				char ch = str.charAt(i);
				if(!map.containsKey(ch)){
					map.put(ch,1);
				}
				else{
					map.put(ch,map.get(ch)+1);
				}
			}
			int min = 21;
			Set<Character> set = map.keySet();
			Iterator it = set.iterator();
			while(it.hasNext()){
				int num = map.get(it.next());
				if(num<min){
					min = num;
				}
			}
			for(int i=0;i<str.length();i++){
				char ch = str.charAt(i);
				if(map.get(ch)!=min){
					sb.append(ch);
				}
			}
			System.out.println(sb.toString());
		}
	}
}