Python regex to find sequences of one upper case letter followed by lower case letters

Write a Python Program to find sequences of one upper case letter followed by lower case letters. If found, print ‘Yes’, otherwise ‘No’.

Examples:

Input : Geeks
Output : Yes

Input : geeksforgeeks
Output : No

Python regex to find sequences of one upper case letter followed by lower case letters

Using re.search() To check if the sequence of one upper case letter followed by lower case letters we use regular expression ‘[A-Z]+[a-z]+$’. 

Python3

# your code goes here# Python program to
# find the most occurring element
import re
from collections import Counter

def most_occr_element(word):

    # re.findall will extract all the elements
    # from the string and make a list
    arr = re.findall(r'[0-9]+', word)

    # to store maxm frequency
    maxm = 0

    # to store maxm element of most frequency
    max_elem = 0

    # counter will store all the number with
    # their frequencies
    # c = counter((55, 2), (2, 1), (3, 1), (4, 1))
    c = Counter(arr)

    # Store all the keys of counter in a list in
    # which first would we our required element
    for x in list(c.keys()):

        if c[x]>= maxm:
            maxm = c[x]
            max_elem = int(x)

    return max_elem

# Driver program
if __name__ == "__main__":
    word = 'geek55of55gee4ksabc3dr2x'
    print(most_occr_element(word))

Output:

Yes
Yes
No

Time complexity: O(n), where n is length of string.
Auxiliary Space: O(1)