lintcode(646)First Position Unique Character

描述：

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

-1

.

样例：

Given s = 

"lintcode"

, return 

0

.

Given s = 

"lovelintcode"

, return 

2

.
思路：

逐个字符遍历，查看以 i 为分割点前后两个字符串是否包含重复字符

或者建立hashmap，存储字符信息

public class Solution {
/**
* @param s a string
* @return it's index
*/
public int firstUniqChar(String s) {
// Write your code here
if(s == null || s.length() == 0){
return -1;
}
for(int i = 0;i<s.length() - 1;i++){
char p = s.charAt(i);
if(s.indexOf(p , i + 1) < 0 && s.indexOf(p) == i){
return i;
}
}
if(s.indexOf(s.charAt(s.length() - 1)) == s.length() - 1){
return s.length() - 1;
}
return -1;
}
}