Jolly Jumper in Python

Question

I'm trying to solve the Jolly Jumper problem on Kattis.

Here is the link to the problem: https://open.kattis.com/contests/ge97jq/problems/jollyjumpers

And here's my answer solution:

values = list(map(int,input().split(" ")))
n = values[0]
x = []

def isJolly(values, n):
    for i in range(1, n-1):
        d = abs(values[i] - values[i+1])

        if (d == 0 or d > n-1 or d in x):
            return False
        else:
            return True
        
if isJolly(values, n):
    print("Jolly")
    
else:
    print("Not Jolly")

I need help because Kattis keeps returning 'Wrong Answer', and I need to figure out why. I think it has something to do with an empty list.

Answer 1

According to the definition, it's jolly if each difference from 1..n-1 occurs once. This implies each difference should be unique. Whenever we encounter a difference that is out of range, or we've already seen, we conclude it's not jolly.

def isJolly(values, n):
    x = {0}
    for i in range(1, n-1):
        d = abs(values[i] - values[i+1])

        if (d > n-1 or d in x):
            return False
        else:
            x.add(d)
    return True