Added implement strStr

Author: shichao-an

implement_strstr/solution.py

@@ -0,0 +1,16 @@
+class Solution:
+    # @param haystack, a string
+    # @param needle, a string
+    # @return a string or None
+    def strStr(self, haystack, needle):
+        n = len(haystack)
+        m = len(needle)
+        for i in range(n + 1 - m):
+            matched = True
+            for k in range(m):
+                if haystack[i + k] != needle[k]:
+                    matched = False
+                    break
+            if matched:
+                return haystack[i:]
+        return None