Maximum Twin Sum of a Linked List

// Accepted solution for LeetCode #2130: Maximum Twin Sum of a Linked List
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public int pairSum(ListNode head) {
        List<Integer> s = new ArrayList<>();
        for (; head != null; head = head.next) {
            s.add(head.val);
        }
        int ans = 0, n = s.size();
        for (int i = 0; i < (n >> 1); ++i) {
            ans = Math.max(ans, s.get(i) + s.get(n - 1 - i));
        }
        return ans;
    }
}

// Accepted solution for LeetCode #2130: Maximum Twin Sum of a Linked List
/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func pairSum(head *ListNode) int {
	var s []int
	for ; head != nil; head = head.Next {
		s = append(s, head.Val)
	}
	ans, n := 0, len(s)
	for i := 0; i < (n >> 1); i++ {
		if ans < s[i]+s[n-i-1] {
			ans = s[i] + s[n-i-1]
		}
	}
	return ans
}

# Accepted solution for LeetCode #2130: Maximum Twin Sum of a Linked List
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def pairSum(self, head: Optional[ListNode]) -> int:
        s = []
        while head:
            s.append(head.val)
            head = head.next
        n = len(s)
        return max(s[i] + s[-(i + 1)] for i in range(n >> 1))

// Accepted solution for LeetCode #2130: Maximum Twin Sum of a Linked List
// Definition for singly-linked list.
// #[derive(PartialEq, Eq, Clone, Debug)]
// pub struct ListNode {
//   pub val: i32,
//   pub next: Option<Box<ListNode>>
// }
//
// impl ListNode {
//   #[inline]
//   fn new(val: i32) -> Self {
//     ListNode {
//       next: None,
//       val
//     }
//   }
// }
impl Solution {
    pub fn pair_sum(head: Option<Box<ListNode>>) -> i32 {
        let mut arr = Vec::new();
        let mut node = &head;
        while node.is_some() {
            let t = node.as_ref().unwrap();
            arr.push(t.val);
            node = &t.next;
        }
        let n = arr.len();
        let mut ans = 0;
        for i in 0..n >> 1 {
            ans = ans.max(arr[i] + arr[n - 1 - i]);
        }
        ans
    }
}

// Accepted solution for LeetCode #2130: Maximum Twin Sum of a Linked List
/**
 * Definition for singly-linked list.
 * class ListNode {
 *     val: number
 *     next: ListNode | null
 *     constructor(val?: number, next?: ListNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.next = (next===undefined ? null : next)
 *     }
 * }
 */

function pairSum(head: ListNode | null): number {
    const arr = [];
    let node = head;
    while (node) {
        arr.push(node.val);
        node = node.next;
    }
    const n = arr.length;
    let ans = 0;
    for (let i = 0; i < n >> 1; i++) {
        ans = Math.max(ans, arr[i] + arr[n - 1 - i]);
    }
    return ans;
}