Update README.md

Author: assassint2017

README.md

@@ -254,6 +254,7 @@
 448. [Find All Numbers Disappeared in an Array](https://github.com/assassint2017/leetcode-algorithm/tree/master/Find%20All%20Numbers%20Disappeared%20in%20an%20Array)
 451. [Sort Characters By Frequency](https://github.com/assassint2017/leetcode-algorithm/tree/master/Sort%20Characters%20By%20Frequency)
 464. [Can I Win](https://github.com/assassint2017/leetcode-algorithm/tree/master/Can%20I%20Win)
+470. [Implement Rand10() Using Rand7()](https://github.com/assassint2017/leetcode-algorithm/tree/master/Implement%20Rand10()%20Using%20Rand7())
 475. [Heaters](https://github.com/assassint2017/leetcode-algorithm/tree/master/Heaters)
 491. [Increasing Subsequences](https://github.com/assassint2017/leetcode-algorithm/tree/master/Increasing%20Subsequences)
 494. [Target Sum](https://github.com/assassint2017/leetcode-algorithm/tree/master/Target%20Sum)