题解 | #找出字符串中第一个只出现一次的字符#

开一个数组记录各个字母出现的次数

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.next();
        
        int[] nums = new int[26];
        for(int i = 0;i < 26;i++)
            nums[i] = 0;
        
        char[] words = s.toCharArray();
        
        for(int i = 0;i < words.length;i++){
            int num = words[i] - 'a';
            nums[num]++;
        }
        
        int index = -1;
        for(int i = 0;i < words.length;i++){
            if(nums[words[i] - 'a'] == 1){
                index = i;
                break;
            }
        }
        
        if(index != -1){
            System.out.println(words[index]);
        }else{
            System.out.println(-1);
        }
        
        
    }
}