Create 28. Implement strStr().py

Author: xulzee

28. Implement strStr().py

@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+# @Time    : 2019/3/1 10:19
+# @Author  : xulzee
+# @Email   : [email protected]
+# @File    : 28. Implement strStr().py
+# @Software: PyCharm
+from typing import List
+
+
+class Solution:
+    def get_next(self, s: str) -> List[int]:
+        next_list = [-1] * len(s)
+        i = 0
+        j = -1
+        while i < len(s) - 1:
+            if j == -1 or s[i] == s[j]:
+                i += 1
+                j += 1
+                next_list[i] = j
+            else:
+                j = next_list[j]
+        return next_list
+
+    def strStr(self, haystack: str, needle: str) -> int:
+        next_list = self.get_next(haystack)
+        j = 0
+        i = 0
+        while i < len(haystack) and j < len(needle):
+            if j == -1 or haystack[i] == needle[j]:
+                j += 1
+                i += 1
+            else:
+                j = next_list[j]
+        if j == len(needle):
+            return i - j
+        else:
+            return -1
+    def strStr1(self, haystack, needle):
+        """
+        :type haystack: str
+        :type needle: str
+        :rtype: int
+        """
+        if not needle:
+            return 0
+
+        len_h = len(haystack)
+        len_n = len(needle)
+
+        for i in range(len_h):
+            if i + len_n > len_h:
+                return -1
+
+            if haystack[i] == needle[0]:
+                if haystack[i:len_n+i] == needle:
+                    return i
+
+        return -1
+
+if __name__ == '__main__':
+    haystack = "mississippi"
+    needle = "issip"
+    print(Solution().strStr(haystack, needle))