add 188

README.md

@@ -134,6 +134,7 @@ My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
 | 172 |[Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/172.%20Factorial%20Trailing%20Zeroes.md)|Easy|  |
 | 179 |[Largest Number](https://leetcode.com/problems/largest-number/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/179.%20Largest%20Number.md)|Medium|  |
 | 187 |[Repeated DNA Sequences](https://leetcode.com/problems/repeated-dna-sequences/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/187.%20Repeated%20DNA%20Sequences.md)|Medium|  |
+| 188 |[Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/188.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20IV.md)|Hard|  |
 | 189 |[Rotate Array](https://leetcode.com/problems/rotate-array)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/189.%20Rotate%20Array.md)|Easy|  |
 | 190 |[Reverse Bits](https://leetcode.com/problems/reverse-bits)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/190.%20Reverse%20Bits.md)|Easy|  |
 | 191 |[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/191.%20Number%20of%201%20Bits.md)|Easy|  |

solutions/188. Best Time to Buy and Sell Stock IV.md

@@ -0,0 +1,3 @@
+# [188. Best Time to Buy and Sell Stock IV](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iv/)
+
+允许k次交易的股票买卖问题，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/)。