String - 387. First Unique Character in a String

#===================================
# Tanzila Islam
# Email: tanzilamohita@gmail.com
# Language: Python 3
#===================================
class Solution:
    def firstUniqChar(self, s: str) -> int:
        
        save_idx = {}
        for val in s:
            if val in save_idx:
                save_idx[val] += 1
            else:
                save_idx[val] = 1

        for idx, val in enumerate(s):
            if save_idx[val] == 1:
                return idx
        return -1