Update README.md

Author: fengvyi

README.md

@@ -352,7 +352,7 @@ My C++ solutions of [LeetCode Online Judge](https://leetcode.com/problemset/algo
 | 685 | [Redundant Connection II](https://leetcode.com/problems/redundant-connection-ii/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/685.%20Redundant%20Connection%20II.cpp) | Hard | Graph / DFS / Union Find | [discuss](https://leetcode.com/problems/redundant-connection-ii/description/) |
 | 686 | [Repeated String Match](https://leetcode.com/problems/repeated-string-match/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C++/686.%20Repeated%20String%20Match.cpp) | Easy | String | [discuss](https://discuss.leetcode.com/topic/106037/3ms-c-o-n-solution) |
 | 687 | [Longest Univalue Path](https://leetcode.com/problems/longest-univalue-path/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/687.%20Longest%20Univalue%20Path.cpp) | Easy | Tree / DFS | [discuss](https://discuss.leetcode.com/topic/106043/simple-c-dfs) |
-| 688 | [Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard/description/) | Medium | Dynamic Programming ||[discuss](https://leetcode.com/problems/knight-probability-in-chessboard/discuss/115213/C++-memoization-easy-to-understand) |
+| 688 | [Knight Probability in Chessboard](https://leetcode.com/problems/knight-probability-in-chessboard/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/688.%20Knight%20Probability%20in%20Chessboard.cpp) |Medium | Dynamic Programming |[discuss](https://leetcode.com/problems/knight-probability-in-chessboard/discuss/115213/C++-memoization-easy-to-understand) |
 | 689 | [Maximum Sum of 3 Non-Overlapping Subarrays](https://leetcode.com/problems/maximum-sum-of-3-non-overlapping-subarrays/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/689.%20Maximum%20Sum%20of%203%20Non-Overlapping%20Subarrays.cpp) | Hard | Array / Dynamic Programming | [discuss](https://discuss.leetcode.com/topic/109486/concise-c-dp-solution-with-comments) |
 | 690 | [Employee Importance](https://leetcode.com/problems/employee-importance/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/690.%20Employee%20Importance.cpp) | Easy | Hash Table / BFS / DFS | [discuss](https://discuss.leetcode.com/topic/109269/c-12-lines-bfs-and-7-lines-dfs) |
 | 692 | [Top K Frequent Words](https://leetcode.com/problems/top-k-frequent-words/description/) | [C++](https://github.com/fengvyi/LeetCode/blob/master/C%2B%2B/692.%20Top%20K%20Frequent%20Words.cpp) | Medium | Hash Table / Heap | [discuss](https://discuss.leetcode.com/topic/108091/12-lines-c-min-heap-o-nlogk-solution) |