Add solution #470

Author: JoshCrozier

README.md

@@ -376,6 +376,7 @@
 466|[Count The Repetitions](./0466-count-the-repetitions.js)|Hard|
 467|[Unique Substrings in Wraparound String](./0467-unique-substrings-in-wraparound-string.js)|Medium|
 468|[Validate IP Address](./0468-validate-ip-address.js)|Medium|
+470|[Implement Rand10() Using Rand7()](./0470-implement-rand10-using-rand7.js)|Medium|
 472|[Concatenated Words](./0472-concatenated-words.js)|Hard|
 476|[Number Complement](./0476-number-complement.js)|Easy|
 482|[License Key Formatting](./0482-license-key-formatting.js)|Easy|

solutions/0470-implement-rand10-using-rand7.js

@@ -0,0 +1,28 @@
+/**
+ * 470. Implement Rand10() Using Rand7()
+ * https://leetcode.com/problems/implement-rand10-using-rand7/
+ * Difficulty: Medium
+ *
+ * Given the API rand7() that generates a uniform random integer in the range [1, 7],
+ * write a function rand10() that generates a uniform random integer in the range [1, 10].
+ * You can only call the API rand7(), and you shouldn't call any other API. Please do not
+ * use a language's built-in random API.
+ *
+ * Each test case will have one internal argument n, the number of times that your implemented
+ * function rand10() will be called while testing. Note that this is not an argument passed to
+ * rand10().
+ */
+
+/**
+ * The rand7() API is already defined for you.
+ * var rand7 = function() {}
+ * @return {number} a random integer in the range 1 to 7
+ */
+var rand10 = function() {
+  while (true) {
+    const n = (rand7() - 1) * 7 + rand7();
+    if (n <= 40) {
+      return (n % 10) + 1;
+    }
+  }
+};