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; } }