diff --git a/src/easy/read_binary_watch.py b/src/easy/read_binary_watch.py
new file mode 100644
index 0000000..077569a
--- /dev/null
+++ b/src/easy/read_binary_watch.py
@@ -0,0 +1,24 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+"""
+    @author: loopgan
+    @contact: ganwei4955@gmail.com
+    @time: 18-10-10 上午12:24
+"""
+
+
+class Solution:
+    def readBinaryWatch(self, num):
+        """
+        :type num: int
+        :rtype: List[str]
+        """
+        return ['%d:%02d' % (h, m) for h in range(12) for m in range(60) if (bin(h) + bin(m)).count('1') == num]
+
+
+if __name__ == "__main__":
+    num = 1
+    ss = Solution()
+    print(ss.readBinaryWatch(num))
+    # print("Hello imp")
diff --git a/src/easy/rotate_string.py b/src/easy/rotate_string.py
new file mode 100644
index 0000000..a679f71
--- /dev/null
+++ b/src/easy/rotate_string.py
@@ -0,0 +1,40 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+"""
+    @author: loopgan
+    @contact: ganwei4955@gmail.com
+    @time: 18-10-10 上午12:58
+"""
+
+
+class Solution:
+    def rotateString(self, A, B):
+        """
+        :type A: str
+        :type B: str
+        :rtype: bool
+        """
+        if len(A) != len(B):
+            return False
+        else:
+            if len(A) == 0:
+                return True
+            for i in range(len(B), 0, -1):
+                if i == 0:
+                    return False
+                if B[0:i] in A:
+                    if B[i:] in A:
+                        return True
+                    else:
+                        return False
+                else:
+                    return False
+
+
+if __name__ == "__main__":
+    A = 'abcde'
+    B = 'cdeab'
+    ss = Solution()
+    print(ss.rotateString(A, B))
+    print("Hello imp")
diff --git a/src/easy/set_mismatch.py b/src/easy/set_mismatch.py
new file mode 100644
index 0000000..da92970
--- /dev/null
+++ b/src/easy/set_mismatch.py
@@ -0,0 +1,29 @@
+#!/usr/bin/python3
+# -*- coding: utf-8 -*-
+
+"""
+    @author: loopgan
+    @contact: ganwei4955@gmail.com
+    @time: 18-9-5 上午12:01
+"""
+
+
+class Solution:
+    def findErrorNums(self, nums):
+        tmp = [i + 1 for i in range(len(nums))]
+        r = 0
+        zz = []
+        for i in nums:
+            if i in zz:
+                r = i
+            else:
+                zz.append(i)
+        lack = list(set(tmp).difference(set(nums)))[0]
+        return r, lack
+
+
+if __name__ == "__main__":
+    s = [1, 2, 2, 4]
+    ss = Solution()
+    print(ss.findErrorNums(s))
+    print("Hello imp")