feat: leetcode Maximum Twin Sum of a Linked List solution (2130) (#988)

leetcode/README.md

@@ -93,3 +93,4 @@ LeetCode
 |1184|[Distance Between Bus Stops](https://leetcode.com/problems/distance-between-bus-stops/) | [C](./src/1184.c)|Easy|
 |1189|[Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons/) | [C](./src/1189.c)|Easy|
 |1207|[Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/) | [C](./src/1207.c)|Easy|
+|2130|[Maximum Twin Sum of a Linked List](https://leetcode.com/problems/maximum-twin-sum-of-a-linked-list/) | [C](./src/2130.c)|Medium|

leetcode/src/2130.c

@@ -0,0 +1,30 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     struct ListNode *next;
+ * };
+ */
+
+int pairSum(struct ListNode* head)
+{
+    struct ListNode* dup = head;
+    int count = 0, i = 0, max = 0;
+    while (head != NULL)
+    {
+        count++;
+        head = head->next;
+    }
+    int* arr = malloc(count * sizeof(int));
+    while (dup != NULL)
+    {
+        arr[i++] = dup->val;
+        dup = dup->next;
+    }
+    for (i = 0; i < count / 2; ++i)
+    {
+        if (arr[i] + arr[count - i - 1] > max)
+            max = arr[i] + arr[count - i - 1];
+    }
+    return max;
+}