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CSCE 3110 Data Structures & Algorithm Analysis Rada Mihalcea Growable Arrays. Lists. Reading: Chap. 3 Weiss

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Linked Lists Avoid the drawbacks of fixed size arrays with Growable arrays Linked lists

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Growable arrays Avoid the problem of fixed-size arrays Increase the size of the array when needed (I.e. when capacity is exceeded) Two strategies: tight strategy (add a constant): f(N) = N + c growth strategy (double up): f(N) = 2N

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Tight Strategy Add a number k (k = constant) of elements every time the capacity is exceeded C0 + (C0+k) + … (C0+Sk) = S = (N – C0) / k Running time? C0 * S + S*(S+1) / 2 O(N 2 )

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Tight Strategy void insertLast(int rear, element o) { if ( size == rear) { capacity += k; element* B = new element[capacity]; for(int i=0; i

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Growth Strategy Double the size of the array every time is needed (I.e. capacity exceeded) C0 + (C0 * 2) + (C0*4) + … + (C0*2 i ) = i = log (N / C0) Running time? C0 [ … + 2 log(N/C0) ] O(N) How does the previous code change?

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Linked Lists Avoid the drawbacks of fixed size arrays with Growable arrays Linked lists

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int i, *pi; float f, *pf; pi = (int *) malloc(sizeof(int)); pf = (float *) malloc (sizeof(float)); *pi =1024; *pf =3.14; printf(an integer = %d, a float = %f\n, *pi, *pf); free(pi); free(pf); request memory return memory Using Dynamically Allocated Memory (review)

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bat cat sat vat NULL Linked Lists

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bat cat sat vat NULL mat Insertion Compare this with the insertion in arrays!

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bat cat sat vat NULL mat dangling reference Deletion

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List ADT ADT with position-based methods generic methodssize(), isEmpty() query methodsisFirst(p), isLast(p) accessor methodsfirst(), last() before(p), after(p) update methodsswapElements(p,q), replaceElement(p,e) insertFirst(e), insertLast(e) insertBefore(p,e), insertAfter(p,e) removeAfter(p)

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typedef struct node, *pnode; typedef struct node { char data [4]; pnode next; }; Creation pnode ptr =NULL; Testing #define IS_EMPTY(ptr) (!(ptr)) Allocation ptr=(pnode) malloc (sizeof(node)); Declaration Implementation

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b a t \0 NULL address of first node ptr data ptr link ptr e name (*e).name strcpy(ptr data, bat); ptr link = NULL; Create one Node

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pnode create2( ) { /* create a linked list with two nodes */ pnode first, second; first = (pnode) malloc(sizeof(node)); second = ( pnode) malloc(sizeof(node)); second -> next= NULL; second -> data = 20; first -> data = 10; first ->next= second; return first; } NULL ptr Example: Create a two-nodes list

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void insertAfter(pnode node, char* data) { /* insert a new node with data into the list ptr after node */ pnode temp; temp = (pnode) malloc(sizeof(node)); if (IS_FULL(temp)){ fprintf(stderr, The memory is full\n); exit (1); } Insert (after a specific position)

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strcpy(temp->data, data); if (node) { noempty list temp->next=node->next; node->next= temp; } else { empty list temp->next= NULL; node =temp; } } NULL temp node

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10 20 NULL NULL 50 node trail = NULL node (a) before deletion (b)after deletion Deletion Delete node other than the first node NULL NULL 10 head node head

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void removeAfter(pnode node) { /* delete what follows after node in the list */ pnode tmp; if (node) { tmp = node -> next; node->next = node->next->next; free(tmp); } } NULL NULL 10 node

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void traverseList(pnode ptr) { printf(The list contains: ); for ( ; ptr; ptr = ptr->next) printf(%4d, ptr->data); printf(\n); } Traverse a list Where does ptr point after this function call?

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Other List Operations swapElements insertFirst insertLast deleteBefore deleteLast

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Running Time Analysis insertAfter O(?) deleteAfter O(?) deleteBeforeO(?) deleteLastO(?) insertFirst O(?) insertLast O(?)

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