Самая частая буква

from collections import Counter
s = '- We all live in the Yellow Submarine!'
cnt = Counter()
for i in range(65, 91):
    cnt[chr(i)] = 0
for ch in s.upper():
    if ch.isalpha():
        cnt[ch] += 1
cnt = cnt.most_common()
n_max = cnt[0][1]
for ch, n in cnt:
    if n < n_max:
        break
    print(ch, end='')
print()
print(n_max)

def task(stri):
    d={}
    for a in stri.upper():
        if a.isalpha():
            if d.get(a)==None:
                d[a]=1
            else:
                d[a]=d[a]+1
    mf=max(d.values())
    r=""
    for k,v in d.items():
        if v==mf:
            r=r+k
    return (mf,r)
    
(a,b)=task("We all live in the Yellow Submarine!")
print(a)
print(str(sorted(b)))

from collections import Counter
#s = '- We all live in the Yellow Submarine!'
s = '123'
cnt = Counter()
for ch in s.upper():
    if ch.isalpha():
        cnt[ch] += 1
if len(cnt) == 0:
    print('Во введенной строке нет букв.')
    exit(0)
cnt = cnt.most_common()
n_max = cnt[0][1]
answer = []
for ch, n in cnt:
    if n < n_max:
        break
    answer.append(ch)
print(''.join(sorted(answer)))
print(n_max)

import string
import random
 
 
text = '- We all live in the Yellow Submarine!'
text1 = ("a" + "b" + "c" * 3 + "w" * 10 + "o" * 10 + "r"* 10 + "g" * 10)
 
 
def  most_frequent_letters(text):
    freqs = dict.fromkeys(string.ascii_uppercase,0)
    max_occur = 0
    letters = ''
   
    for ch in text.upper():
        if ch in freqs:
            freqs[ch]+=1
            if freqs[ch] > max_occur:
                max_occur = freqs[ch]
                letters = ch 
            if freqs[ch] == max_occur and ch not in letters:
                letters += ch
    return ''.join(sorted(letters)), max_occur
                
#pprint(sorted(freq.items(), key=lambda t:t[1]))      
print(*most_frequent_letters(text), sep="\n") 
print(*most_frequent_letters(text1), sep="\n") 
text2 = list(string.ascii_letters)
random.shuffle(text2)
text2= "".join(text2)
print(*most_frequent_letters(text2), sep="\n")

def task_quick(stri):
    freq=[]
    for i in range(26):
        freq.append(0)
    for a in stri.upper():
        if a.isalpha():
            k=ord(a)-ord('A')
            freq[k]+=1
    maf=max(freq)
    res=""
    for i in range(26):
        if freq[i]==maf:
            res=res+chr(i+ord('A'))
    return (maf,res)        
    
(a,b)=task_quick("We all live in the Yellow Submarine!")
print(a)
print(b)

def task_quick(stri):
    freq=[]
    for i in range(26):
        freq.append(0)
    maf=0
    for a in stri:
        if a.isalpha():
            k=ord(a.upper())-ord('A')
            freq[k]+=1
            if freq[k]>maf:
               maf=freq[k] 
    res=""
    for i in range(26):
        if freq[i]==maf:
            res=res+chr(i+ord('A'))
    return (maf,res)        
    
(a,b)=task_quick("We all live in the Yellow Submarine!")
print(a)
print(b)

def  most_frequent_letters(text):
    freqs = dict.fromkeys(string.ascii_uppercase,0)
    max_occur = 0
    
    for ch in text.upper():       
        if ch in freqs:
            freqs[ch] += 1
            if freqs[ch] > max_occur:
                max_occur = freqs[ch]    
    
    
    return ''.join(
        letter  for letter, freq in freqs.items() if freq == max_occur
    ), max_occur