First Unique Character in a String(leetcode387)

Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1.

Examples:

s = "leetcode"
return 0.

s = "loveleetcode",
return 2.

Note: You may assume the string contain only lowercase letters.

這裏寫都是小寫字母，若是還有其餘奇怪的字符，那麼我就選擇使用Map來處理，和使用數組也是相似的

ublic static int firstUniqChar(String s) {

    int[] arr = new int[26];
    for(int i =0;i<s.length();i++){
        arr[s.charAt(i) - 'a']++;
    }
    for(int j =0;j<s.length();j++){
        if(arr[s.charAt(j) - 'a'] == 1){
            return j;
        }
    }
    return -1;

}

 

public static void main(String[] args) {

    System.out.println(firstUniqChar("leetcode"));
    System.out.println(firstUniqChar("loveleetcode"));

}

輸出：

git：https://github.com/woshiyexinjie/leetcode-xin