Finishing the third problem

lab12/3.c

@@ -1,7 +1,163 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+/* Single Linked list related code */
+typedef struct _selist * Slist;
+
+struct _selist {
+    int el;
+    Slist next;
+};
+
+int head(Slist lst) {
+    return lst->el;
+}
+
+Slist tail(Slist lst) {
+    return lst->next;
+}
+
+Slist insert(int element, Slist list) {
+    Slist * addr = &list;
+    while (*addr) { // While addr' not null, go to the end.
+        addr = &(*addr)->next; // the list is modified by this. I think...
+    } // we should be at the end now.
+    Slist node = malloc(sizeof(struct _selist));
+    node->el = element;
+    node->next = NULL; // we set to head if we want circular, I think?
+    *addr = node;
+    return list;
+}
+
+Slist delete(int element, Slist list) {
+    Slist * addr = &list;
+    while (*addr) {
+        if ( (*addr)->el == element) {
+            Slist temp = (*addr)->next;
+            free(*addr);
+            *addr = temp;
+            break;
+        }
+        addr = &(*addr)->next;
+    }
+    return list;
+}
+
+size_t size(Slist list) {
+    size_t elements = 0;
+    while (list) {
+      elements += 1;
+      list = list->next;
+    }
+    return elements;
+}
+
+void print_list(Slist list) {
+    printf("SLIST PRINT\n");
+    Slist * addr = &list;
+    while (*addr) {
+      printf("%d ", (*addr)->el);
+      addr = &(*addr)->next;
+    }
+    printf("\n");
+}
+
+/* Double Linked list related code */
+
+typedef struct _dilist * Dlist;
+
+struct _dilist {
+    int element;
+    Dlist next;
+    Dlist prev;
+};
+
+Dlist insert_dl(int element, Dlist list) {
+    Dlist * addr = &list;
+    Dlist prev = NULL;
+    while (*addr) { // While addr' not null, go to the end.
+    if ( !(*addr)->next ) {
+        prev = *addr;
+    }
+        addr = &(*addr)->next; // the list is modified by this. I think...
+    } // we should be at the end now.
+    Dlist node = malloc(sizeof(struct _dilist));
+    node->element = element;
+    node->next = NULL; // we set to head if we want circular, I think?
+    node->prev = prev; // 1 - NULL, 2 - 1, 3- 2, 4 - 3
+    // printf("%d", prev->element);
+    *addr = node;
+    return list;
+}
+
+void print_dlist(Dlist list) {
+    printf("DLIST PRINT\n");
+    Dlist * addr = &list;
+    while (*addr) {
+        // if (((*addr)->prev))
+            // printf("prev %d\n", ((*addr)->prev)->element);
+        printf("%d ", (*addr)->element);
+        addr = &(*addr)->next;
+    }
+    printf("\n");
+}
+
+/* Code related to the split function */
+
+void split_li_to_di(Slist sli, Dlist * dli1, Dlist * dli2) {
+    short first_insertion;
+    size_t sizzle = size(sli); // ma fizzle, drizzle
+    if (!sizzle) { return; } // exit if size is zeero.
+    size_t middle = sizzle / 2;
+
+
+    // Handle first double linked list.
+    *dli1 = malloc(sizeof(struct _dilist));
+    first_insertion = 1;
+    for (int i = 0; i < middle; i++) {
+        if ( first_insertion) {
+            *dli1 = insert_dl(sli->el, NULL);
+            first_insertion = 0; // :>
+        } else {
+            *dli1 = insert_dl(sli->el, *dli1);
+        }
+        sli = sli->next;
+    }
+
+    // Handle seccond double linked list.
+    if ( !(middle % 2) ) { middle += 1; } // if not even, add one.
+    *dli2 = malloc(sizeof(struct _dilist));
+    first_insertion = 1;
+    for (int i = 0; i < middle; i++) {
+        if ( first_insertion) {
+            *dli2 = insert_dl(sli->el, NULL);
+            first_insertion = 0; // :>
+        } else {
+            *dli2 = insert_dl(sli->el, *dli2);
+        }
+        sli = sli->next;
+    }
+}
 
 int main(void) {
-  return 0;
+    // Write a function to split a simple linked list into two double linked lists at a
+    // specific point in the original list. The specific point is provided by the key value.
+    Slist li = insert(1, insert(2, insert(3, insert(4, insert(5, NULL)))));
+
+    Dlist dli1 = NULL;
+    Dlist dli2 = NULL;
+
+    split_li_to_di(li, &dli1, &dli2);
+
+    print_list(li);
+    print_dlist(dli1);
+    print_dlist(dli2);
+
+    // Test
+    // Dlist dli = insert_dl(1, insert_dl(2, insert_dl(3, insert_dl(4, NULL))));
+    // print_dlist(dli);
+    // Slist li = insert(1, insert(2, insert(3, insert(4, NULL))));
+    // li = delete(1, li);
+    // print_list(li);
+    return 0;
 }