数据结构——链表

github.com/trekhleb/ja… 的学习笔记

链表是数据元素的线性集合，但他不是像数组那样连续储存在内存中，每个链表元素都由他自己的值和指向下一个元素的引用组成。他可以插入或删除指定的元素，但由于他的访问只能是线性的，它要访问一个元素，就要从头开始遍历直到找到该元素，不能像数组那样快速的随机访问。

基本操作

插入

Add(value)
  Pre: value is the value to add to the list
  Post: value has been placed at the tail of the list
  n ← node(value)
  if head = ø
    head ← n
    trail ← n
  else
    trail.next = n
    trail ← n
  end if
end Add

Prepend(value)
  Pre: value is the value to add to the list
  Post: value has been placed at the head of the list
  n ← node(value)
  n.next ← head
  n ← head
  if trail = ø
    trail ← n
  end
end Perepend

搜索

Contains(head, value)
  Pre: head is the head node in the list
       value is the value to search for
  Post: the item is either in the linked list, true; otherwise false
  n ← head
  if n = ø
    return false
  while (n != ø and n.value != value)
    n ← n.next
  end while
  if (n = ø)
    return false
  end if
  return true

删除

Remove(head, value)
  Pre: head is the head node in the list
       value is the value to remove from the list
  Post: value is removed from the list, true, otherwise false
  n ← head
  if n = ø
    return false
  end if
  if n.value = value
    if head = trail
      head ← ø
      trail ← ø
    else
      head ← head.next
    return true
  end if
  while n.next != ø and n.next.value != value
    n ← n.next
  end while
  if n.next != ø
    if trail = n.next
      trail ← n
    end if
    n.next ← n.next.next
    return true
  end if
  else
    return false
end Remove

遍历

Traverse(head)
  Pre: head is the head node in the list
  Post: the items in the list have been traversed
  n ← head
  while n != ø
    yield n.value
    n ← n.next
  end while
end Traverse

反向遍历

ReverseTraversal(head, trail)
  Pre: head and tail belong to the same list
  Post: the items in the list have been traversed in reverse order
  if trail != ø
    curr = trail
    while head != curr
      prev ← head
      while prev.next != curr
        prev ← prev.next
      end while
      yield curr.value
      curr ← prev
    end while
    yield curr.value
  end if
end ReverseTraversal

复杂度

时间复杂度

空间复杂度

O(n)