add new solutions

solutions/21/q2130/solution.go

@@ -0,0 +1,27 @@
+package q2130
+
+import "math"
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+var arr = []int{}
+
+func pairSum(head *ListNode) int {
+	arr = arr[:0]
+	for p := head; p != nil; p = p.Next {
+		arr = append(arr, p.Val)
+	}
+	maxSum := math.MinInt
+	l, r := 0, len(arr)-1
+	for l < r {
+		maxSum = max(maxSum, arr[l]+arr[r])
+		l++
+		r--
+	}
+	return maxSum
+}
+
+var _ = pairSum