# Python - Check if a number and its double exists in an array

PythonServer Side ProgrammingProgramming

When it is required to check if a number and its double exists in an array, it is iterated over, and multiple with 2 and checked.

## Example

Below is a demonstration of the same

def check_double_exists(my_list):
for i in range(len(my_list)):
for j in (my_list[:i]+my_list[i+1:]):
if 2*my_list[i] == j:
print("The double exists")

my_list = [67, 34, 89, 67, 90, 17, 23]
print("The list is :")
print(my_list)
check_double_exists(my_list)

## Output

The list is :
[67, 34, 89, 67, 90, 17, 23]
The double exists

## Explanation

• A method named ‘check_double_exists’ is defined that takes a list as a parameter.

• It iterates through the list, and multiple every element with 2 and checks to see if there exists a number that matches this doubled value.

• If such a value is found, relevant message is displayed.

• Outside the method, a list is defined, and is displayed on the console.

• The method is called by passing the list.

• The output is displayed on the console.

Updated on 20-Sep-2021 11:03:26