题解 | #第一个只出现一次的字符#

    public int FirstNotRepeatingChar(String str) {
        int len = str.length();
        int[] hash = new int[128];
        
        for (int i = 0; i < len; ++i) {
            hash[str.charAt(i)]++;
        }
        
        for (int i = 0; i < len; ++i) {
            if (hash[str.charAt(i)] == 1) {
                return i;
            }
        }
        return -1;
    }
}