diff --git a/README.md b/README.md
index 8af6590..80f3c7e 100644
--- a/README.md
+++ b/README.md
@@ -185,6 +185,7 @@ My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
 | 278 |[First Bad Version](https://leetcode.com/problems/first-bad-version)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/278.%20First%20Bad%20Version.md)|Easy|  |
 | 279 |[Perfect Squares](https://leetcode.com/problems/perfect-squares/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/279.%20Perfect%20Squares.md)|Medium|  |
 | 283 |[Move Zeroes](https://leetcode.com/problems/move-zeroes)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/283.%20Move%20Zeroes.md)|Easy|  |
+| 287 |[Find the Duplicate Number](https://leetcode.com/problems/find-the-duplicate-number/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/287.%20Find%20the%20Duplicate%20Number.md)|Medium|  |
 | 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|  |
@@ -234,4 +235,4 @@ My LeetCode solutions with Chinese explanation. 我的LeetCode中文题解。
 | 643 |[Maximum Average Subarray I](https://leetcode.com/problems/maximum-average-subarray-i)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/643.%20Maximum%20Average%20Subarray%20I.md)|Easy|  |
 | 661 |[Image Smoother](https://leetcode.com/problems/image-smoother)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/661.%20Image%20Smoother.md)|Easy|  |
 | 665 |[Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/665.%20Non-decreasing%20Array.md)|Easy|  |
-| 714 |[Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/714.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20with%20Transaction%20Fee.md)|Medium|  |
\ No newline at end of file
+| 714 |[Best Time to Buy and Sell Stock with Transaction Fee](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-with-transaction-fee/)|[C++](https://github.com/ShusenTang/LeetCode/blob/master/solutions/714.%20Best%20Time%20to%20Buy%20and%20Sell%20Stock%20with%20Transaction%20Fee.md)|Medium|  |