python code for a list of friends greetings each other

Question

I have a python program with following logic & I can't get the nested loops right :( first line: number of friends? second line: enter each person name in same line separated by space [in a list] . this is how the greetings will go:

input:
3
John Sara Tom

output:

Sara: Hi John!
Tom:   Hi Sara!
tom: Hi John!
John: bye guys!
Sara: bye John!
Tom: Bye John!
Sara: Bye guys!
Tom: Bye Sara!
Tom: Bye guys!

the greetings(Hi) starts with the second person in the list obviously; the nested loop will iterate from the newest person in the list to the first person (descending order)

and same thing should follow for saying goodbye ?(can this be done using list comprehension?!)

n=int(input())
user=list(input().split())

for i in range(2,n):
 for j in range(i-1,1,-1):
    print(user[i-1] +": Hi " + user[j-1] + "!")
for i in range(n):
print(user[i-1] + ": Bye guys!")
 for j in range(i+1):
   print(user[j-1] + ": Bye " + user[i-1]+ "!")

Sara: Hi John! Tom: Hi Sara! tom: Hi John! John: bye guys! Sara: bye John! Tom: Bye John! Sara: Bye guys! Tom: Bye Sara! Tom: Bye guys! — , Oct 17 '21 at 06:01
Does this answer your question? [Single Line Nested For Loops](https://stackoverflow.com/questions/17006641/single-line-nested-for-loops) — bad_coder, Oct 17 '21 at 17:22

j1-lee · Accepted Answer · 2021-10-17T07:02:22.047

Your code is in the right direction. Meticulous treatment of for and indexing would finish it. Try the following:

n = 3 # n = input('How many friends? ')
names = 'John Sara Tom'.split() # names = input('Who are they? ').split()

for i in range(1, n):
    for j in range(i - 1, -1, -1):
        print(f'{names[i]}: Hi {names[j]}!')

for i in range(n):
    print(f'{names[i]}: Bye guys!')
    for j in range(i + 1, n):
        print(f'{names[j]}: Bye {names[i]}!')

Output:

Sara: Hi John!
Tom: Hi Sara!
Tom: Hi John!
John: Bye guys!
Sara: Bye John!
Tom: Bye John!
Sara: Bye guys!
Tom: Bye Sara!
Tom: Bye guys!

As for list comprehension, of course you can do that:

his = [f'{names[i]}: Hi {names[j]}!' for i in range(1, n) for j in range(i - 1, -1, -1)]
byes = [f'{names[i]}: Bye guys!' + '\n'
        + '\n'.join(f'{names[j]}: Bye {names[i]}!' for j in range(i + 1, n))
        for i in range(n)]
print('\n'.join(his))
print('\n'.join(byes))

But apparently this is way less readable.

each person greets whoever was in the list before them . the person before Sara is John , so Sara only say Hi to John... Tom say hi to Sara and then John . — , Oct 17 '21 at 06:03
@Pythonnewby Oh I made a mistake there; please check the updated answer. — j1-lee, Oct 17 '21 at 06:05

python code for a list of friends greetings each other

1 Answers1