Question

Write a function that takes two arguments, both strings. Print "YES" if the second string argument contains only characters found in the first string argument. Print "NO" if the second string argument contains characters not in the first. Here are some sample calls. In your program, call the function 3 times with the same arguments shown below.

makeStr("hello", "")
makeStr("hello", "olleloheloeloheloel")
makeStr("hello", "olleloheloteloheloel")

# YES
# YES
# NO

Answer 1

Below are the screenshots of code & output:

Below is the python program with a simple implementation of makeStr function. The function creates 2 sets each corresponding to characters of the 2 arguments passed. Let us call these sets as set1 (corresponding to first argument) and set2 (corresponding to second argument). Then according to question, we need to print 'YES' when the second string argument contains only characters in first string argument i.e. when set2 is a subset of set1 (which is same as set difference of set2 & set1(set2-set1) being an empty set). Else, 'NO' is printed.

NOTE**The pasted code often loses its indentation after being post. In case below code loses its indentation, please refer to above screenshots for proper indentation

#implementing function makeStr

def makeStr(A,B):

#creates 2 sets- one of characters in A & other of characters in B

#if the set difference of set corresponding to B and set

#corresponding to A is not empty,

#then B contains characters not found in A

if len(set(B)-set(A))==0:

print("YES")

else:

print("NO")

# sample calls

makeStr("hello", "") # YES

makeStr("hello", "olleloheloeloheloel") # YES

makeStr("hello", "olleloheloteloheloel") # NO