add tasks 5,6

Author: GamilaCoding

0x17-doubly_linked_lists/5-get_dnodeint.c

@@ -0,0 +1,26 @@
+#include "lists.h"
+
+/**
+  * get_dnodeint_at_index - get nth node of a dlistint_t linked list
+  * @head: header of double linked list
+  * @index: index of the node, starting from 0
+  * Return: a address of nth node
+  */
+dlistint_t *get_dnodeint_at_index(dlistint_t *head, unsigned int index)
+{
+	dlistint_t *headcopy;
+	unsigned int i;
+
+	headcopy = head;
+	if (headcopy != NULL)
+	{
+		while (headcopy->prev != NULL)
+			headcopy = headcopy->prev;
+
+		for (i = 0; (i < index) && (headcopy != NULL); i++)
+			headcopy = headcopy->next;
+		return (headcopy);
+	}
+	else
+		return (NULL);
+}

0x17-doubly_linked_lists/6-sum_dlistint.c

@@ -0,0 +1,28 @@
+#include "lists.h"
+
+/**
+  * sum_dlistint - sum of all the data (n) of a dlistint_t linked list
+  * @head: header of double linked list
+  * Return: the sum of all nodes
+  */
+int sum_dlistint(dlistint_t *head)
+{
+	dlistint_t *headcopy;
+	int sum = 0;
+
+	headcopy = head;
+	if (headcopy != NULL)
+	{
+		while (headcopy->prev != NULL)
+			headcopy = headcopy->prev;
+
+		while (headcopy != NULL)
+		{
+			sum += headcopy->n;
+			headcopy = headcopy->next;
+		}
+		return (sum);
+	}
+	else
+		return (0);
+}