Status getElemFromLinkedList(const LinkedList L, int i, ElemType *e){
assert(L);
LinkedList p = L;
if(i < 1 || i > lengthOfLinkedList(L) ){
printf("Error: invalid index.\n");
return(ERROR);
}
while(i--){
p = p->next;
}
*e = p->data;
return OK;
}
Status removeItemFromLinkedList(LinkedList L, int i, ElemType *e){
assert(L);
LinkedList p = L, q = NULL;
if(i < 1 || i > lengthOfLinkedList(L)){
printf("Error: invalid index for remove.\n");
return ERROR;
}
while(--i){
p = p->next;
}
q = p->next;
p->next = q->next;
*e = q->data;
L->data -= 1;
free(q);
return OK;
}
/* 在L中第i个位置之前插入新的数据元素e, 1<= i <= length(L) + 1*/
Status insertItemToLinkedList(LinkedList L, int i, ElemType e){
assert(L);
LinkedList p = L;
if(i < 1 || i > lengthOfLinkedList(L) + 1){
printf("Error: invalid index for insertion, index must be in[1,%d],you give %d.\n", lengthOfLinkedList(L),i);
return ERROR;
}
LNode * newNode = (LNode *)malloc(sizeof(LNode));
while(--i){
p = p->next;
}
newNode->data = e;
newNode->next = p->next;
p->next = newNode;
L->data += 1;
return OK;
}
/*
* Maintain two pointers – reference pointer and main pointer.
* Initialize both reference and main pointers to head.
* First move reference pointer to n nodes from head.
* Now move both pointers one by one until reference pointer reaches end.
* Now main pointer will point to nth node from the end. Return main pointer.
*/
void SinglyLinkedList::printNthNodeFromEndLinkedList(int n){
SingleNode *refptr=head;
SingleNode *mainptr=head;
int count =1;
if(n>lengthOfLinkedList() || n<=0){
cout<<"Number is not correct.Must be from 1 to length "<<endl;
return;
}
while(count <= n){
refptr = refptr->next;
count ++;
}
while(refptr){
refptr = refptr->next;
mainptr = mainptr->next;
}
cout<<"Data is ::"<<mainptr->data;
}
Status isLinkedListEmpty(const LinkedList L){
assert(L);
return lengthOfLinkedList(L) == 0;
}
bool SinglyLinkedList::checkIfListPalindrome_usingNoStorage(){
int length=lengthOfLinkedList();
int middle,index_tmp;
int index=0;
if(length%2==0){
middle=length/2;
}
else{
middle=length/2+1;
}
SingleNode *tmp = head;
SingleNode *prev =NULL;
SingleNode *next;
//Go to second half starting location
while(index != middle){
prev=tmp;
tmp =tmp->next;
index++;
}
SingleNode *end_firsthalf=prev;//Needed to recover the original list
//Reverse second half of linked list
while(tmp != NULL){
next = tmp -> next;
tmp -> next = prev;
prev = tmp;
tmp = next;
}
SingleNode *start_secondhalf=prev;//Needed to recover the original list
//Now the second half of the list is reversed.
SingleNode *index_firsthalf =head;
SingleNode *index_secondhalf =prev;
index=0;
if(length%2==0){
index_tmp=middle;
}
else{
index_tmp=middle-1;
}
int flag=1;
while(index<index_tmp){
if(index_firsthalf->data != index_secondhalf->data){
flag=0;
break;
}
index_firsthalf=index_firsthalf->next;
index_secondhalf=index_secondhalf->next;
index++;
}
SingleNode *next_recoverlist;
SingleNode *prev_recoverlist=NULL;
int index_recoverlist=0;
while(index_recoverlist!=length/2){
next_recoverlist=start_secondhalf->next;
start_secondhalf->next = prev_recoverlist;
prev_recoverlist=start_secondhalf;
start_secondhalf=next_recoverlist;
index_recoverlist=index_recoverlist+1;
}
//Reverse the list again to undo the changes
if(flag==0)
return false;
else
return true;
}
