update ana, add ipi7

ws2019/ipi/uebungen/queue_einfach.cpp

@@ -0,0 +1,83 @@
+#include<stdio.h>
+#include<cstdlib>
+
+// Ein Schlangenelement
+struct QueueElem {
+    QueueElem* next;  // Zeiger auf nächstes Element
+    int value;          // Daten zu diesem Element  
+} ;
+
+// Eine Schlange
+struct Queue {
+    int count;          // Anzahl Elemente in der Liste
+    QueueElem* first; // Zeiger auf erstes Element der Liste
+} ;
+
+// Initialisiere eine Schlange
+void empty_queue (Queue* l)
+{
+    l->first = 0;   // 0 ist keine gueltige Adresse: Liste ist leer
+    l->count = 0;
+}
+
+// Fuege ein Element ans Ende der Schlange an
+void add_to_queue (Queue* queue, QueueElem* elem)
+{
+    // Laufpointer
+    QueueElem* current = queue->first;
+    if (queue->first == 0) { // if queue is empty, put the new element as the first one
+        queue->first = elem;
+        return;
+    }
+    // find last element of list
+    while (current->next != 0) {
+        current = current->next;
+    }
+    current->next = elem; // set new element as the follower of the old last one
+    queue->count = queue->count + 1; // increment queue size
+}
+
+// Entferne das erste Element der Schlange
+QueueElem* remove_from_queue(Queue* queue)
+{
+    QueueElem* p;  // das entfernte Element
+    if (queue->first == 0) { // check if list is empty
+        return p;  // then just return null pointer
+    } else {
+        p = queue->first; // return the first element of the queue
+        queue->first = p->next; // set the second to be the new first
+        queue->count = queue->count-1; // decrement queue size
+        return p; // return the removed element
+    }
+}
+
+// print a queue
+void print_queue(Queue* queue) {
+    // index pointer
+    QueueElem* current = queue->first;
+    printf("Queue: ");
+    // print every element until the last
+    while (current != 0) {
+        printf("%d ", current->value);
+        current = current->next;
+    }
+    printf("\n");
+}
+
+int main() {
+    // create a queue
+    Queue* queue = new Queue();
+    empty_queue(queue);
+    // and some elements
+    for (int i = 0; i < 100000; i++) {
+        QueueElem* elem = new QueueElem();
+        elem -> value = rand();
+        add_to_queue(queue, elem);
+    }
+    // and remove them again
+    for (int i = 0; i < 100000; i++) {
+        remove_from_queue(queue);
+    }
+    // check if queue is empty
+    print_queue(queue);
+}