寻找第一个出现次数最少的字符

骑猪看日落 2021-09-27 06:32 324阅读 0赞

同理寻找第一个出现次数最少的字符，一次循环的还没想好

import java.util.HashMap;
    import java.util.Map;
    import java.util.Scanner;
    
    /** * Created by zfr on 2018/08/05. * 寻找第一个出现次数最少的字符 */
    public class Solution { 
        public static void main(String[] args) {
                // TODO Auto-generated method stub
            Solution  a = new  Solution ();
            Scanner scanner = new Scanner(System.in);
            String str = scanner.nextLine();
            if(str == null || str.length() == 0 ){
                System.out.println("输入有误！");
                return;
            }
            System.out.println(a.cal1(str));
            System.out.println(a.cal2(str));
        }
        ///三次循环
        private char cal1(String str) {
            Map<Character,Integer> map = new HashMap<>();
            char[] ch = str.toCharArray();
            for (int i = 0;i<ch.length;i++) {
                if(map.containsKey(ch[i])){
                    map.put(ch[i],map.get(ch[i])+1);
                }else {
                    map.put(ch[i],1);
                }
            }
            int count = Integer.MAX_VALUE;
            for (Map.Entry<Character,Integer> entry:map.entrySet()) {
                count = Math.min(count,entry.getValue());
            }
            for(char c : ch){
                if(map.get(c) == count ){
                    return c ;
                }
            }
            return ch[0];
        }
        //两次循环
        private char cal2(String str) {
            Map<Character,Integer> map = new HashMap<>();
            char[] ch = str.toCharArray();
            for (int i = 0;i<ch.length;i++) {
                if(map.containsKey(ch[i])){
                    map.put(ch[i],map.get(ch[i])+1);
                }else {
                    map.put(ch[i],1);
                }
            }
            int index = Integer.MAX_VALUE ;
            char minChar = ch[0];
            for(int i = 0 ;i<ch.length;i++){
                if(map.get(ch[i]) < index ){
                    index = map.get(ch[i]);
                    minChar = ch[i] ;
                }
            }
            return minChar;
        }
    
    }