力扣387.字符串中的第一个唯一字符0705

Posted 2021-07-25 小布丁value

import java.util.HashMap;

public class Day0706 {
    public int firstUniaChar(String s){


        HashMap<Character, Integer> frequency = new HashMap<>();
        for(int i=0;i<s.length();i++){
            //数组转字符串
            char ch =s.charAt(i);
            frequency.put(ch,frequency.getOrDefault(ch,0)+1);

        }
        for(int i=0;i<s.length();i++){
            if(frequency.get(s.charAt(i))==1){
                return i;
            }
        }
        return -1;
    }
}

https://leetcode-cn.com/problems/first-unique-character-in-a-string/solution/zi-fu-chuan-zhong-de-di-yi-ge-wei-yi-zi-x9rok/