AlgoExpert First Non-Repeating Character

def firstNonRepeatingCharacter(string):
    dict = {}
    for i in range(len(string)):
        if string[i] in dict:
            dict[string[i]] = -1
        else:
            dict[string[i]] = i
    
    for i in dict:
        if dict[i] != -1:
            return dict[i]
    
    return -1