Title: In a sorted linked list nodes duplicate, delete the duplicate node list, the node does not retain repeated, returns the head pointer list. For example, the list 1-> 2-> 3-> 3-> 4-> 4-> 5 is treated 1-> 2-> 5
A: When traversing the first node is repeated, there must be a pointer to its previous node
Because there is no transfer function prototype come in two pointers and the head node may also be deleted, so to build a new node Head
Boolean type flag_repeat determines whether duplicate nodes, the node is deleted if repeated, the mobile node if the pointer is not repeated
/ *
Struct ListNode {
int Val;
struct ListNode * Next;
ListNode (int X):
Val (X), Next (NULL) {
}
};
* /
class Solution {
public:
ListNode * deleteDuplication (ListNode * PHEAD)
{
IF ( (PHEAD == nullptr a) || (pHead-> Next == nullptr a))
{
return PHEAD;
}
// because no two pointer passed in, and the first node may also be removed, so the node to build a new head
ListNode = new new ListNode Head * (0);
head-> Next = PHEAD;
ListNode Head * = P prev;
ListNode * • pNode = PHEAD;
the while (! • pNode = nullptr a)
{
bool flag_repeat = false; // determines whether there are duplicate node
IF ((pNode-> Next = nullptr a) && (pNode-> Val pNode- ==> next-> Val)!)
{
flag_repeat = to true;
}
// No repeating node
IF (== flag_repeat to false)
{
P prev = • pNode;
• pNode = pNode-> Next;
}
// node duplicate
the else
{
ListNode pDelete = * • pNode; // duplicate nodes not preserved
while ((pNode-> next! nullptr a =) && (pNode-> Val pNode- ==> next-> Val))
{
• pNode = pNode-> Next;
// only delete the original one
delete pDelete;
pDelete = pNode;
}
pPrev->next = pNode->next;
pNode = pNode->next;
//删第二个
delete pDelete;
pDelete = pNode;
}
}
return Head->next;
}
};
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