/*

Given a string s, find the first non-repeating character in

it and return its index. If it does not exist, return -1.

Example 1:

Input: s = "leetcode"

Output: 0

Explanation:

The character 'l' at index 0 is the first character that does

not occur at any other index.

Example 2:

Input: s = "loveleetcode"

Output: 2

Example 3:

Input: s = "aabb"

Output: -1

*/

public class LeetCode387 {

static public int firstUniqChar(String s) {

int freq [] = new int[26];

char ch[] = s.toCharArray();

for(int i=0;i<ch.length;i++){

freq[ch[i]-'a']++;

}

for(int i=0;i<ch.length;i++){

if(freq[ch[i]-'a']==1){

return i;

}

}

return -1;

}

public static void main(String[] args) {

System.out.println(firstUniqChar("aabb"));

}

}