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.
time = O(n), space = O(1)
class Solution { public int firstUniqChar(String s) { if(s == null || s.length() == 0) { return -1; } int[] map = new int[26]; for(int i = 0; i < s.length(); i++) { map[s.charAt(i) - ‘a‘]++; } for(int i = 0; i < s.length(); i++) { if(map[s.charAt(i) - ‘a‘] == 1) { return i; } } return -1; } }
387. First Unique Character in a String - Easy
原文：https://www.cnblogs.com/fatttcat/p/11404382.html