# Program to find sum of non-adjacent elements in a circular list in python

PythonServer Side ProgrammingProgramming

Suppose we have a list of numbers called nums that is representing a circular list. We have to find the largest sum of non-adjacent numbers.

So, if the input is like nums = [10, 3, 4, 8], then the output will be 14, as we can take 10 and 4. We cannot take 10 and 8 as they are adjacent.

To solve this, we will follow these steps −

• n := size of nums
• nums1 := nums[from index 0 to n - 2]
• nums2 := nums[from index 1 to end]
• Define a function f() . This will take i
• if i >= size of nums1 , then
• return 0
• return maximum of nums1[i] + f(i + 2) and f(i + 1)
• Define a function g() . This will take j
• if j >= size of nums2 , then
• return 0
• return maximum of nums2[j] + g(j + 2) and g(j + 1)
• From the main method do the following −
• return maximum of f(0) and g(0)

Let us see the following implementation to get better understanding −

## Example

Live Demo

class Solution:
def solve(self, nums):
n = len(nums)
nums1 = nums[: n - 1]
nums2 = nums[1:]
def f(i):
if i >= len(nums1):
return 0
return max(nums1[i] + f(i + 2), f(i + 1))
def g(j):
if j >= len(nums2):
return 0
return max(nums2[j] + g(j + 2), g(j + 1))
return max(f(0), g(0))
ob = Solution()
nums = [10, 3, 4, 8]
print(ob.solve(nums))

## Input

[10, 3, 4, 8]

## Output

14