[leetcode]387. First Unique Character in a String第一个不重复字母

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.

 

思路

1.  use int array to simplify a hashmap

2. one pass to mark each char's occurrence

3. second pass to check 1st index whose char's occurrence == 1 

 

代码

1 class Solution { 2 public int firstUniqChar(String s) { 3 int map [] = new int[256]; 4 for(int i = 0; i < s.length(); i ++) 5 map [s.charAt(i) ] ++; 6 for(int i = 0; i < s.length(); i ++) 7 if(map [s.charAt(i) ] == 1) 8 return i; 9 return -1; 10 } 11 }

 

转载于:https://www.cnblogs.com/liuliu5151/p/10090777.html

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