Merge pull request doocs#247 from Gapur/master

Power of four

Author: yanglbme

solution/0342.Power of Four/README.md

@@ -0,0 +1,17 @@
+# 342. Power of Four
+
+Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
+
+## Example 1:
+```
+Input: 16
+Output: true
+```
+
+## Example 2:
+```
+Input: 5
+Output: false
+```
+
+Follow up: Could you solve it without loops/recursion?

solution/0342.Power of Four/Solution.js

@@ -0,0 +1,3 @@
+const isPowerOfFour = function(num) {
+  return (Math.log(num) / Math.log(4)) % 1.0 == 0.0;
+};

solution/README.md

@@ -876,6 +876,8 @@
 │   └── Solution.cpp
 ├── 0331.Verify Preorder Serialization of a Binary Tree
 │   └── Solution.java
+├── 0342.Power of Four
+│   └── Solution.js
 ├── 0343.Integer Break
 │   ├── README.md
 │   ├── README_EN.md