318. Find Sum of All Nodes in Linked List

Given the head of a singly linked list, return the sum of all node values.

Traverse the list and accumulate the sum.

Input: Head of a singly linked list.

Output: Integer — sum of all node values.

Examples

Example 1

Input: [1,2,3,4,5]
Output: 15
Explanation: 1+2+3+4+5 = 15.

Example 2

Input: [10,20,30]
Output: 60
Explanation: 10+20+30 = 60.

Example 3

Input: [-3,5,-2]
Output: 0
Explanation: -3+5+(-2) = 0.