删除链接列表中的先前重复条目

I have the following structure for my linked list.

我的链表有以下结构。

typedef struct value value;

struct value{
  value* prev;
  value* next;
  int value;
};

...
//ent = entry
if(entry_head == NULL) { 
 entry_head = ent;
 entry_tail = ent;
 entry_tail->prev = NULL;
}
else { // add to top
  ent -> next = entry_head;
  ent -> prev = NULL;
  entry_head -> prev = ent;
  entry_head = ent;
}

This gives me the results:

这给了我结果:

Input: a       Result: b
       b               a

However when I input two of the same variables, I want to delete the previous variable and have the newly input variable only. ie.

但是,当我输入两个相同的变量时,我想删除前一个变量并仅使用新输入的变量。即。

Input: a // old    Result: a // new   Actual Result: a // new
       a // new                                      a // old

How do I modify this so that It removes the older variable?

如何修改它以便删除旧变量?

1 个解决方案

#1

You need to modify the add node code, in the part of the function that deals with all nodes added to a non NULL list.

您需要在处理添加到非NULL列表中的所有节点的函数部分中修改添加节点代码。

value *tmp =head ;
while(tmp!=NULL) {
  if(tmp->Value== newval) break;
  tmp=tmp->next;
}
If(tmp!=NULL) return 0;
// add node here

return  1

Alternatively after adding a node, create a similar while loop.

或者,在添加节点之后,创建类似的while循环。

For every node in the list all nodes after this have to be compared and removed. This will be in efficient.

对于列表中的每个节点,必须比较和删除此后的所有节点。这将是有效的。

To remove a node all you do is some pointer twizzling , then free the node if no longer needed to avoid memory leaks

要删除一个节点,你所做的只是一些指针闪烁,然后释放节点,如果不再需要避免内存泄漏

// a->B->c
//  <- <-

value *save=a->next;

a->Next=save->next;

// node c

Save->Next->prev=save->prev;


free(save);

This code hasn't been tested, I have no linux on my phone.

这段代码还没有经过测试,我手机上没有linux。

#1