void testReverse(void){
printf("Testing reverse!\n");
//reverse the list once...
List l = setUpList();
printList(l);
reverseList(l);
printList(l);
assert(getElement(l, 0) == 4);
assert(getElement(l, 1) == 7);
assert(getElement(l, 2) == 8);
assert(getElement(l, 3) == 1);
assert(listLength(l) == START_LENGTH);
//reverse it again!
reverseList(l);
printList(l);
assert(getElement(l, 0) == 1);
assert(getElement(l, 1) == 8);
assert(getElement(l, 2) == 7);
assert(getElement(l, 3) == 4);
assert(listLength(l) == START_LENGTH);
//testing that appended items are reversed as well
append(l, 32);
reverseList(l);
assert(getElement(l, 0) == 32);
assert(listLength(l) == START_LENGTH + 1);
printf("Reversing passed!\n");
}
void testReverseList() {
cout << endl;
cout << "Test reverseList():" << endl;
cout << "===================" << endl;
char a[] = "a";
char b[] = "b";
char c[] = "c";
char d[] = "d";
char e[] = "e";
char f[] = "f";
char g[] = "g";
Node<char*> head;
head.data = a;
head.next = nullptr;
appendToList(&head, &b[0]);
appendToList(&head, &c[0]);
appendToList(&head, &d[0]);
appendToList(&head, &e[0]);
appendToList(&head, &f[0]);
appendToList(&head, &g[0]);
printList(&head);
Node<char*>* rev = reverseList(&head);
printList(rev);
Node<char*>* orig = reverseList(rev);
printList(orig);
}
int main(int argc, char **argv)
{
int i;
int n;
NodePtr node;
JobPtr job;
ListPtr list;
if (argc != 2) {
fprintf(stderr, "Usage: %s <list size> \n",argv[0]);
exit(1);
}
n = atoi(argv[1]);
list = createList();
for (i=0; i<n; i++) {
job = createJob(i, "cmd args");
node = createNode(job);
addAtFront(list, node);
}
printList(list);
reverseList(list);
printList(list);
reverseList(list);
printList(list);
exit(0);
}
ListNode *reverseBetween(ListNode *head, int m, int n) {
if (head == NULL)
return NULL;
if (head->next == NULL || m == n)
return head;
m--; n--;
if (m == 0)
{
head = reverseList(head, n - m + 1);
return head;
}
int c = 0;
ListNode* curNode = head;
ListNode* tail = NULL;
while (c < m)
{
assert(curNode);
tail = curNode;
curNode = curNode->next;
c++;
}
curNode = reverseList(curNode, n - m + 1);
tail->next = curNode;
return head;
}
// O(n)-time, O(1)-space
bool isPalindrome2(ListNode *head) {
if (head == NULL) {
return true;
}
// 计算中间节点
ListNode *mid = findMiddleNode(head);
// 反转后半段链表
ListNode *reverseHead = reverseList(mid->next);
// 连接前后两半段链表
mid->next = reverseHead;
// 比较前后两个半段链表
// 注意：后半段链表节点个数 <= 前半段链表节点个数
bool isPal = true;
while (reverseHead != NULL) {
if (head->val != reverseHead->val) {
isPal = false;
}
head = head->next;
reverseHead = reverseHead->next;
}
// 恢复原链表
reverseHead = reverseList(mid->next);
mid->next = reverseHead;
return isPal;
}
/* Deletes nodes which have a node with greater value node on left side */
void delLesserNodes(struct Node **head_ref)
{
/* 1) Reverse the linked list */
reverseList(head_ref);
/* 2) In the reversed list, delete nodes which have a node with greater value node on left side.
Note that head node is never deleted because it is the leftmost node.*/
_delLesserNodes(*head_ref);
/* 3) Reverse the linked list again to retain the original order */
reverseList(head_ref);
}
void linkedListTest() {
node * list = nullptr;
print(list);
std::cout << "↔";
reverseList(list);
print(list);
for (const auto & elem : {5,1,3,2,4,8,6,9,7}) {
appendList(list, elem);
print(list);
std::cout << "↔";
reverseList(list);
print(list);
}
}
bool isPalindrome(ListNode* head) {
if (head == nullptr || head->next == nullptr) return true;
ListNode* slow = head;
ListNode* fast = head;
while (fast->next != nullptr && fast->next->next != nullptr) {
fast = fast->next->next;
slow = slow->next;
}
ListNode* right = reverseList(slow->next);
slow->next = nullptr;
bool result = compare(head, right);
slow->next = reverseList(right);
return result;
}
void test( int* arr, int size ) {
node* root = newList( arr, size );
print( root );
reverseList( &root );
print( root );
freeList( root );
}
void reorderList(ListNode* head) {
if (head==NULL || head->next==NULL || head->next->next==NULL)
{
return ;
}
ListNode* l1=head;
ListNode* l2=getMid(head);
ListNode* reverseL2=reverseList(l2);
ListNode* newhead=new ListNode(-1);
ListNode* tail=newhead;
while (l1!=NULL && reverseL2!=NULL)
{
tail->next=l1;
l1=l1->next;
tail=tail->next;
tail->next=reverseL2;
tail=tail->next;
reverseL2=reverseL2->next;
}
if (l1!=NULL)
{
tail->next=l1;
}
if (reverseL2!=NULL)
{
tail->next=reverseL2;
}
head=newhead->next;
}
int main() {
struct node * head = NULL;
struct node * second = NULL;
struct node * third = NULL;
head = (struct node *) malloc(sizeof(struct node));
second = (struct node *) malloc(sizeof(struct node));
third = (struct node *) malloc(sizeof(struct node));
head->data = 1;
head->next = second;
second->data = 2;
second->next = third;
third->data = 3;
third->next = NULL;
printf("Normal list order:\n");
printList(head);
printf("\nReversed order:\n");
reverseList(&head);
printList(head);
return 0;
}
ListNode* reverseList(ListNode* head) {
if (!head || !(head->next)) return head;
ListNode* tmp = reverseList(head->next);
head->next->next = head;
head->next = NULL;
return tmp;
}
ListNode* reverseList(ListNode *head, int k) {
ListNode *prev, *current, *next, *tail;
current = head, prev = NULL, tail = head;
int cnt = 0;
while (current != NULL) {
if (cnt > k)
break;
current = current->next;
cnt++;
}
if (cnt < k)
return head;
cnt = 0;
current = head;
while (cnt < k && current != NULL) {
next = current->next;
current->next = prev;
prev = current;
current = next;
cnt++;
}
if (current != NULL)
tail->next = reverseList(current, k);
return prev;
}
int main()
{
node *listHead = create();
if (!listHead)
return 0;
for (int i = 0; i < 10; i++)
add(listHead, i);
deleteNode(listHead, 5);
insertNode(listHead, 5, 50);
printf("Length = %d\n", length(listHead));
printList(listHead);
reverseList(listHead);
printList(listHead);
node *pMid;
pMid = getMid(listHead);
printf("Mid data is %d\n", pMid->data);
add(listHead, 99);
printList(listHead);
pMid = getMid(listHead);
printf("Mid data is %d\n", pMid->data);
destroy(listHead);
return 0;
}
void reorderList(ListNode* head)
{
if (head == NULL || head->next == NULL) return;
ListNode * slow = head;
ListNode * fast = head->next;
while (fast && fast->next)
{
fast = fast->next->next;
slow = slow->next;
}
ListNode * half = slow->next;
slow->next = NULL;
fast = reverseList(half);
slow = head;
while (fast)
{
ListNode * slowNext = slow->next;
ListNode * fastNext = fast->next;
slow->next = fast;
fast->next = slowNext;
slow = slowNext;
fast = fastNext;
}
}
ListNode* reverseList(ListNode* head){
if(!head || !head->next) return head;
ListNode* newHead = reverseList(head->next);
head->next->next = head;
head->next = NULL;
return newHead ;
}
ListNode *reverseKGroup(ListNode *head, int k) {
/* https://oj.leetcode.com/problems/reverse-nodes-in-k-group/
e.g.,
Given this linked list: 1->2->3->4->5
For k = 2, you should return: 2->1->4->3->5
For k = 3, you should return: 3->2->1->4->5
*/
if (head == NULL || head->next == NULL || k < 2) return head;
ListNode *dummy = new ListNode(0), *tail = dummy;
while (head != NULL) {
ListNode *tmp = head;
for (int i = 1; i < k && tmp != NULL; i++) {
tmp = tmp->next;
}
if (tmp == NULL) {
tail->next = head;
break;
}
ListNode *tmp2 = tmp->next;
tmp->next = NULL;
reverseList(head);
tail->next = tmp;
tail = head;
head = tmp2;
}
head = dummy->next;
delete dummy;
return head;
}
ListNode* reverseList(ListNode* head) {
if (head == nullptr || head->next == nullptr) return head;
ListNode* node = reverseList(head->next);
head->next->next = head;
head->next = nullptr;
return node;
}
int main(void)
{
int i = 0, ret = 0;
struct node *ptr = NULL;
print_list();
for(i = 0; i<100000000; i++)
add_to_list(i);
//print_list();
ptr = search_in_list(99999999, NULL);
if(NULL == ptr)
{
printf("Search [val = %d] failed, no such element found\n",i);
}
else
{
printf("Search passed [val = %d]\n",ptr->val);
}
printf("Lets reverse the linked list\n");
reverseList();
return 0;
}
ListNode *reverseBetween(ListNode *head, int m, int n) {
ListNode *list = head;
if (m != n) {
ListNode *pm = NULL, *prem = NULL, *pn = NULL, *nextn = NULL;
int index = 1;
ListNode *p = head, *pre = NULL;
// 找到m、n两个结点
while (index <= n && p != NULL) {
if (index == m) {
prem = pre;
pm = p;
}
if (index == n) {
pn = p;
nextn = p->next;
}
index++;
pre = p;
p = p->next;
}
// 倒序链表 m --> ... -> n
pn->next = NULL;
ListNode *from, *to;
reverseList(pm, &from, &to);
// 加上头尾
to->next = nextn;
if (prem == NULL) {
list = from;
} else {
prem->next = from;
}
}
return list;
}
int main()
{
struct ListNode *p1,*p2,*head;
for(int i=0;i<2;i++)
{
if(i ==0)
{
p1=(struct ListNode *)malloc(sizeof(struct ListNode));
p1->val=i;
p1->next=NULL;
head=p1;
}
else
{
p2=(struct ListNode *)malloc(sizeof(struct ListNode));
p2->val=i;
p2->next=NULL;
p1->next=p2;
p1=p1->next;
}
}
printf("origin:");
printlist(head);
p2=reverseList(head);
printf("after:");
printlist(p2);
}
int main(int argc, char **argv)
{
int i;
int n;
struct node *list;
struct node *node;
if (argc != 2) {
fprintf(stderr, "Usage: %s <list size> \n",argv[0]);
exit(1);
}
n = atoi(argv[1]);
list = NULL;
for (i=0; i<n; i++) {
node = (struct node*) malloc(sizeof(struct node));
if (node == NULL) {
printf("Error allocating node for linked list\n");
exit(1);
}
node->item = i;
list = addAtFront(list, node);
}
printList(list);
list=reverseList(list);
printList(list);
return 0;
}
void reorderList(ListNode *head) {
//step 1: count
//iterator headPtr = head;
int len = lengthOfList( head );
if( len < 3 ){
return;
}
//step 2: reverse
int mid = (len+1)/2;
iterator midPtr = getMid( head, mid );
iterator mn = midPtr->next;
midPtr->next = NULL;
midPtr = reverseList( mn );
//step 3: merge
iterator hn = head->next;
mn = midPtr->next;
while( mn != NULL ){
head->next = midPtr;
midPtr->next = hn;
head = hn;
midPtr = mn;
hn = head->next;
mn = midPtr->next;
}
head->next = midPtr;
midPtr->next = hn;
return ;
}
bool isPalindrome(ListNode* head) {
ListNode* slow = head;
ListNode* fast = head;
while(fast && fast->next){
slow = slow->next;
fast = fast->next->next;
}
if(fast) {
slow = slow->next;
}
fast = head;
slow = reverseList(slow);
// At this point, the original list is split into two.
// fast: the 1st half in original order.
// slow: the 2nd half in reverse order.
while(slow) {
if(fast->val != slow->val)
return false;
fast = fast->next;
slow = slow->next;
}
return true;
}
// Iteratively
// ListNode* reverseList(ListNode* head) {
// ListNode* cur = NULL;
// for(auto p = head; p != NULL;) {
// auto tmp = p->next;
// p->next = cur;
// cur = p;
// p = tmp;
// }
// return cur;
// }
// Recursively
ListNode* reverseList(ListNode* head) {
if(!head || !head->next) return head;
auto p = reverseList(head->next);
head->next->next = head;
head->next = NULL;
return p;
}
bool isPalindrome(ListNode* head)
{
if (! head)
return true;
int len = ::lenList(head);
if (len == 1)
return true;
ListNode* mid1 = head;
for (int i=0; i<len/2-1; ++i)
mid1 = mid1->next;
ListNode* mid2 = mid1->next;
ListNode* left = head;
ListNode* right = mid2;
mid1->next = NULL;
if (len % 2)
{
right = right->next;
mid2->next = NULL;
}
showList(left);
showList(right);
right = reverseList(right);
showList(right);
while (left && right)
{
if (left->val != right->val)
return false;
left = left->next;
right = right->next;
}
return true;
}
bool isPalindrome(ListNode* head) {
if (head == NULL) //empty
return true;
if (head->next == NULL) //only a head
return true;
ListNode* fast = head; // slow and fast make slow point to the mid
ListNode* slow = head;
ListNode* slowPrev = NULL; // slowPrev is the element before slow
while (fast!=NULL && fast->next!=NULL){ // 'fast!=NULL' means the size of the list is odd,'fast->next' means even
fast = fast->next->next;
if (fast==NULL || fast->next==NULL){
slowPrev = slow;
}
slow = slow->next;
}
slowPrev->next = NULL; // slowPrev->next points to NULL
ListNode* tail = reverseList(slow); // reverse the list after the slow pointer(the mid of the list)
while(head!=NULL && tail!=NULL){
if (head->val != tail->val){
delete tail;
return false;
}
head = head->next;
tail = tail->next;
}
delete fast,slow,slowPrev,tail;
return true;
}
void main(int argc, char** argv){
node *head = NULL;
node *test = NULL;
node *merged = NULL;
addNode(5, &head);
addNode(6, &head);
addNode(7, &head);
addNode(10, &head);
addNode(4, &test);
addNode(8, &test);
addNode(11, &test);
merged = merge_sorted(head, test);
printList(merged);
//head->next->next->next->next = head->next;
if(detectLoop(head)){
printf("loop found\n");
exit(0);
}
// printList(head);
deleteNode(7, head);
// printList(head);
head = reverseList(head, NULL);
//printList(head);
destroyList(head);
}
PNODE subRevList(PNODE head, int revCount) {
PNODE p = head;
int count = 0;
PNODE curHead = p;
PNODE prevTail = NULL;
while (p) {
count += 1;
if (count%revCount == 0) {
if (prevTail) {
prevTail->next = p;
prevTail->next_address = p->address;
} else {
head = p;
}
PNODE nextHead = p->next;
p->next = NULL;
p->next_address = -1;
reverseList(curHead);
prevTail = curHead;
curHead = nextHead;
p = nextHead;
} else {
p = p->next;
}
}
if (count%revCount && prevTail) {
prevTail->next = curHead;
prevTail->next_address = curHead->address;
}
return head;
}
int main(int argc, char** argv){
struct ListNode *head, *probe;
int lstSize[4] = {0,1,2,8};
int i;
srand(time(NULL));
for (i = 0; i < 4; i++){
int j;
/* Initialize the linked list. */
head = NULL;
head = (struct ListNode *)malloc(sizeof(struct ListNode));
head->val = 0x7a636664;
head->next = NULL;
for (probe = head, j = 0; j < lstSize[i]; j++){
probe->next = (struct ListNode *)malloc(sizeof(struct ListNode));
probe = probe->next;
probe->val = rand() % 100;
probe->next = NULL;
}
printf("Case%2d: \n",i+1);
printf("The original linked list:\n");
printLst(head);
/* Test */
printf("The reversed linked list:\n");
reverseList(head);
printLst(head);
printf("\n");
deleteLst(head);
}
system("pause");
return 0;
}
