Sync LeetCode submission - Merge Two Sorted Lists (c)

Author: JMoogs

problems/merge_two_sorted_lists/solution.c

@@ -0,0 +1,52 @@
+struct ListNode* mergeTwoLists(struct ListNode* list1, struct ListNode* list2) {
+	struct ListNode* l1_current = list1;
+	struct ListNode* l2_current = list2;
+	struct ListNode* head;
+	// Set head to the pointer to the smaller first value of list1 and list2
+	if (l1_current && l2_current) {
+		if (l1_current->val < l2_current->val) {
+			head = l1_current;
+			l1_current = l1_current->next;
+		} else {
+			head = l2_current;
+			l2_current = l2_current->next;
+		}
+
+	// Trivial cases
+	} else if (l1_current) {
+		return list1;
+	} else if (l2_current) {
+		return list2;
+	} else {
+		return 0;
+	}
+	struct ListNode* current = head;
+	while (1) {
+		// We're finished
+		if (!l1_current && !l2_current) {
+			return head;
+		}
+		// Cases where we only have one list remaining
+		// We can just assign the rest of the list to next here
+		if (!l1_current) {
+			current->next = l2_current;
+			return head;
+		}
+		if (!l2_current) {
+			current->next = l1_current;
+			return head;
+		}
+		// Cases where we have two lists
+		// Compare the values in each and add the smaller to the list being returned,
+		// increasing pointers where necessary
+		if (l1_current->val < l2_current->val) {
+			current->next = l1_current;
+			current = current->next;
+			l1_current = l1_current->next;
+		} else {
+			current->next = l2_current;
+			current = current->next;
+			l2_current = l2_current->next;
+		}
+	}
+}