diff --git a/README.md b/README.md
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@@ -188,6 +188,7 @@ My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
 | 290 |[Word Pattern](https://leetcode.com/problems/word-pattern)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/290.%20Word%20Pattern.md)|Easy|  |
 | 292 |[Nim Game](https://leetcode.com/problems/nim-game)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/292.%20Nim%20Game.md)|Easy|  |
 | 303 |[Range Sum Query - Immutable](https://leetcode.com/problems/range-sum-query-immutable)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/303.%20Range%20Sum%20Query%20-%20Immutable.md)|Easy|  |
+| 309 |[Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/309.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20with%20Cooldown.md)|Medium|  |
 | 326 |[Power of Three](https://leetcode.com/problems/power-of-three)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/326.%20Power%20of%20Three.md)|Easy|  |
 | 342 |[Power of Four](https://leetcode.com/problems/power-of-four)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/342.%20Power%20of%20Four.md)|Easy|  |
 | 344 |[Reverse String](https://leetcode.com/problems/reverse-string)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/344.%20Reverse%20String.md)|Easy|  |
diff --git a/solutions/309. Best Time to Buy and Sell Stock with Cooldown.md b/solutions/309. Best Time to Buy and Sell Stock with Cooldown.md
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+# [309. Best Time to Buy and Sell Stock with Cooldown](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-cooldown/)
+
+带冷却的股票买卖问题，属于LeetCode六道股票买卖题目之一，见我的博客文章[动态规划之股票买卖系列](https://shusentang.github.io/2019/11/03/Buy-and-Sell-Stock/)。
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