Add prepend and fix bug (#227)

Add prepend operation and fix some mistake in pseudocode.

src/data-structures/linked-list/README.zh-CN.md

@@ -29,6 +29,19 @@ Add(value)
 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
+ head ← n
+ if tail = ø
+   tail ← n
+ end
+end Prepend
+```
+
 ### 搜索
 
 ```text
@@ -67,10 +80,10 @@ Remove(head, value)
     end if
     return true
   end if
-  while n.next = ø and n.next.value = value
+  while n.next != ø and n.next.value != value
     n ← n.next
   end while
-  if n.next = ø
+  if n.next != ø
     if n.next = tail
       tail ← n
     end if
@@ -88,7 +101,7 @@ Traverse(head)
   Pre: head is the head node in the list
   Post: the items in the list have been traversed
   n ← head
-  while n = 0
+  while n != 0
     yield n.value
     n ← n.next
   end while
@@ -101,11 +114,11 @@ end Traverse
 ReverseTraversal(head, tail)
   Pre: head and tail belong to the same list
   Post: the items in the list have been traversed in reverse order
-  if tail = ø
+  if tail != ø
     curr ← tail
-    while curr = head
+    while curr != head
       prev ← head
-      while prev.next = curr
+      while prev.next != curr
         prev ← prev.next
       end while
       yield curr.value