Add solution #504

Author: JoshCrozier

0504-base-7.js

@@ -0,0 +1,15 @@
+/**
+ * 504. Base 7
+ * https://leetcode.com/problems/base-7/
+ * Difficulty: Easy
+ *
+ * Given an integer num, return a string of its base 7 representation.
+ */
+
+/**
+ * @param {number} num
+ * @return {string}
+ */
+var convertToBase7 = function(num) {
+  return num.toString(7);
+};

README.md

@@ -166,6 +166,7 @@
 501|[Find Mode in Binary Search Tree](./0501-find-mode-in-binary-search-tree.js)|Easy|
 502|[IPO](./0502-ipo.js)|Hard|
 503|[Next Greater Element II](./0503-next-greater-element-ii.js)|Medium|
+504|[Base 7](./0504-base-7.js)|Easy|
 506|[Relative Ranks](./0506-relative-ranks.js)|Easy|
 509|[Fibonacci Number](./0509-fibonacci-number.js)|Easy|
 520|[Detect Capital](./0520-detect-capital.js)|Easy|