diff --git a/problems/0028.实现strStr.md b/problems/0028.实现strStr.md
index 5cc04994..ff13db39 100644
--- a/problems/0028.实现strStr.md
+++ b/problems/0028.实现strStr.md
@@ -692,107 +692,66 @@ class Solution {
 ```
 
 Python3：
-（版本一）前缀表（不减一）
+（版本一）前缀表（减一）
+```python
+class Solution:
+    def getNext(self, next, s):
+        j = -1
+        next[0] = j
+        for i in range(1, len(s)):
+            while j >= 0 and s[i] != s[j+1]:
+                j = next[j]
+            if s[i] == s[j+1]:
+                j += 1
+            next[i] = j
+    
+    def strStr(self, haystack: str, needle: str) -> int:
+        if not needle:
+            return 0
+        next = [0] * len(needle)
+        self.getNext(next, needle)
+        j = -1
+        for i in range(len(haystack)):
+            while j >= 0 and haystack[i] != needle[j+1]:
+                j = next[j]
+            if haystack[i] == needle[j+1]:
+                j += 1
+            if j == len(needle) - 1:
+                return i - len(needle) + 1
+        return -1
+```
+（版本二）前缀表（不减一）
 
 ```python
 class Solution:
+    def getNext(self, next: List[int], s: str) -> None:
+        j = 0
+        next[0] = 0
+        for i in range(1, len(s)):
+            while j > 0 and s[i] != s[j]:
+                j = next[j - 1]
+            if s[i] == s[j]:
+                j += 1
+            next[i] = j
+    
     def strStr(self, haystack: str, needle: str) -> int:
         if len(needle) == 0:
             return 0
-        next = self.getNext(needle)
+        next = [0] * len(needle)
+        self.getNext(next, needle)
         j = 0
         for i in range(len(haystack)):
-            while j >= 1 and haystack[i] != needle[j]:
-                j = next[j-1]
+            while j > 0 and haystack[i] != needle[j]:
+                j = next[j - 1]
             if haystack[i] == needle[j]:
                 j += 1
             if j == len(needle):
                 return i - len(needle) + 1
         return -1
-    
-    def getNext(self, needle):
-        next = [0] * len(needle)
-        j = 0
-        next[0] = j
-        for i in range(1, len(needle)):
-            while j >= 1 and needle[i] != needle[j]:
-                j = next[j-1]
-            if needle[i] == needle[j]:
-                j += 1
-            next[i] = j
-        return next
-```
-（版本二）前缀表（减一）
-```python
-class Solution:
-    def strStr(self, haystack: str, needle: str) -> int:
-        a = len(needle)
-        b = len(haystack)
-        if a == 0:
-            return 0
-        next = self.getnext(a,needle)
-        p=-1
-        for j in range(b):
-            while p >= 0 and needle[p+1] != haystack[j]:
-                p = next[p]
-            if needle[p+1] == haystack[j]:
-                p += 1
-            if p == a-1:
-                return j-a+1
-        return -1
-
-    def getnext(self,a,needle):
-        next = ['' for i in range(a)]
-        k = -1
-        next[0] = k
-        for i in range(1, len(needle)):
-            while (k > -1 and needle[k+1] != needle[i]):
-                k = next[k]
-            if needle[k+1] == needle[i]:
-                k += 1
-            next[i] = k
-        return next
 ```
 
 
-（版本三）前缀表（减一）
-
-
-```python
-class Solution:
-    def strStr(self, haystack: str, needle: str) -> int:
-        a = len(needle)
-        b = len(haystack)
-        if a == 0:
-            return 0
-        i = j = 0
-        next = self.getnext(a, needle)
-        while(i < b and j < a):
-            if j == -1 or needle[j] == haystack[i]:
-                i += 1
-                j += 1
-            else:
-                j = next[j]
-        if j == a:
-            return i-j
-        else:
-            return -1
-
-    def getnext(self, a, needle):
-        next = ['' for i in range(a)]
-        j, k = 0, -1
-        next[0] = k
-        while(j < a-1):
-            if k == -1 or needle[k] == needle[j]:
-                k += 1
-                j += 1
-                next[j] = k
-            else:
-                k = next[k]
-        return next
-```
-
-（版本四）暴力法
+（版本三）暴力法
 ```python
 class Solution(object):
     def strStr(self, haystack, needle):
@@ -807,7 +766,7 @@ class Solution(object):
                 return i
         return -1    
 ```
-（版本五）使用 index
+（版本四）使用 index
 ```python
 class Solution:
     def strStr(self, haystack: str, needle: str) -> int:
@@ -816,7 +775,7 @@ class Solution:
         except ValueError:
             return -1
 ```
-（版本六）使用 find
+（版本五）使用 find
 ```python
 class Solution:
     def strStr(self, haystack: str, needle: str) -> int: