LeetCode之First Unique Character in a String

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1、题目

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.

2、代码实现

public class Solution {
    public int firstUniqChar(String s) {
		if (s == null || s.length() == 0) {
			return -1;
		}
		HashMap<Character, Integer> map = new HashMap<Character, Integer>();
		for (int i = 0; i < s.length(); i++) {
			Integer in = map.get(s.charAt(i));
			if (in == null) 
				map.put(s.charAt(i), 1);
			else
				map.put(s.charAt(i), 2);
		}
		for (int i = 0; i < s.length(); i++) {
			if(map.get(s.charAt(i)) == 2) {
				continue;
			} else {
				if (map.get(s.charAt(i)) == 1) {
					return i;
				}
			}
		} 
		return -1;
	}
}