# LUCKYN - Editorial

Author: jeevanjyot
Testers: mexomerf, rivalq
Editorialist: iceknight1093

TBD

None

# PROBLEM:

An integer is said to be lucky if it contains the digit 7.
Given a positive integer X, is it lucky?

# EXPLANATION:

All that needs to be done is to check, for each digit of X, whether it equals 7.

Extracting all the digits of an integer can be done in a couple of different ways:

• The simplest way is to read X as a string instead of an integer. Then, you can simply iterate over its characters and check whether each one equals '7' or not.
• Alternately, run the following algorithm:
• If X = 0, stop.
• Otherwise, let d = X%10. d is the last digit of X, check whether it equals 7 or not.
• Next, divide X by 10. This essentially removes the last digit of X.
• Run the above three steps in a loop; hence extracting every digit of X.

# TIME COMPLEXITY:

\mathcal{O}(1) per testcase.

# CODE:

Code (Python) (String)
for _ in range(int(input())):
x = input()
print('Yes' if '7' in x else 'No')
Code (Python) (Loop)
for _ in range(int(input())):
x = int(input())
ans = 'No'
while x > 0:
d = x%10
if d == 7: ans = 'Yes'
x //= 10
print(ans)