Find the first non-repeated character in a string

Question

I read of a job interview question to write some code for the following:

Write an efficient function to find the first nonrepeated character in a st

Answer 1

Question: 1st non-repeating character in a string

Method 1: making a count array

a = "GGGiniiiiGinaaaPrrrottiijayi"
count = [0]*256
for ch in a: count[ord(ch)] +=1
for ch in a :
    if( count[ord(ch)] == 1 ):
        print(ch)
        break

Method2: List comprehension

# 1st  non repeating character
pal = [x for x in a if a.count(x) == 1][0]
print(pal)

Method 3: dictionary

d={}
for ch in a: d[ch] = d.get(ch,0)+1
aa = sorted(d.items(), key = lambda ch  :ch[1])[0][0]
print(aa)