add 89

Author: luliyucoordinate

README.md

@@ -82,6 +82,7 @@ LeetCode
 |0083|[Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list/) | c | [c++](./src/0083-Remove-Duplicates-from-Sorted-List/0083.cpp) |[python](./src/0083-Remove-Duplicates-from-Sorted-List/0083.py)|||Easy|
 |0086|[Partition List](https://leetcode.com/problems/partition-list/) | c | [c++](./src/0086-Partition-List/0086.cpp) |[python](./src/0086-Partition-List/0086.py)|||Medium|
 |0088|[Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/) | c | [c++](./src/0088-Merge-Sorted-Array/0088.cpp) |[python](./src/0088-Merge-Sorted-Array/0088.py)|||Easy|
+|0089|[Gray Code](https://leetcode.com/problems/gray-code/) | c | [c++](./src/0089-Gray-Code/0089.cpp) |[python](./src/0089-Gray-Code/0089.py)|||Medium|
 |0090|[Subsets II](https://leetcode.com/problems/subsets-ii/) | c | [c++](./src/0090-Subsets-II/0090.cpp) |[python](./src/0090-Subsets-II/0090.py)|||Medium|
 |0091|[Decode Ways](https://leetcode.com/problems/decode-ways/) | c | [c++](./src/0091-Decode-Ways/0091.cpp) |[python](./src/0091-Decode-Ways/0091.py)|||Medium|
 |0092|[Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/) | c | [c++](./src/0092-Reverse-Linked-List-II/0092.cpp) |[python](./src/0092-Reverse-Linked-List-II/0092.py)|||Medium|

src/0089-Gray-Code/0089.cpp

@@ -0,0 +1,15 @@
+static int x = []() {std::ios::sync_with_stdio(false); cin.tie(0); return 0; }();
+class Solution 
+{
+public:
+    vector<int> grayCode(int n) 
+    {
+        if (n == 0) return {0};
+        vector<int> res;
+        for (int i = 0; i < 1<<n; ++i)
+        {
+            res.push_back(i^i>>1);
+        }
+        return res;
+    }
+};

src/0089-Gray-Code/0089.py

@@ -0,0 +1,13 @@
+class Solution:
+    def grayCode(self, n):
+        """
+        :type n: int
+        :rtype: List[int]
+        """
+        if n == 0:
+            return [0]
+        
+        res = list()
+        for i in range(1 << n):
+            res.append(i ^ (i>>1))
+        return res