# Solution Exercise 30: check if two lists have common values in python

Mar 30, 2023

#### Exercise 30

Write a Python algorithm as a function that takes two lists as input arguments and returns a boolean value indicating whether or not they have at least one common element.

#### Solution

```def has_common_element(list1, list2):
"""
Check if two lists have at least one common element.
"""
for item1 in list1:
for item2 in list2:
if item1 == item2:
return True
return False
# You can call this function with two lists, for example:
list1 = [1, 2, 3, 4, 5]
list2 = [5, 6, 7, 8, 9]
print(has_common_element(list1, list2)) # prints True

list3 = [10, 11, 12]
list4 = [13, 14, 15]
print(has_common_element(list3, list4)) # prints False```

Explanation:

1. This function iterates through each item: n the first list and compares it with every item in the second list.
2. If a match is found: it returns True.
3. If the function found no match: after has checked all pairs of items, the function returns False.
4. In the first example: the function returns True because both lists have the common value 5.
5. In the second example: the function returns False because there are no common values between the two lists.

Younes Derfoufi
my-courses.net