Add solution #6

Author: JoshCrozier

README.md

@@ -10,6 +10,7 @@
 2|[Add Two Numbers](./0002-add-two-numbers.js)|Medium|
 3|[Longest Substring Without Repeating Characters](./0003-longest-substring-without-repeating-characters.js)|Medium|
 4|[Median of Two Sorted Arrays](./0004-median-of-two-sorted-arrays.js)|Hard|
+6|[ZigZag Conversion](./0006-zigzag-conversion.js)|Medium|
 7|[Reverse Integer](./0007-reverse-integer.js)|Easy|
 8|[String to Integer (atoi)](./0008-string-to-integer-atoi.js)|Medium|
 10|[Regular Expression Matching](./0010-regular-expression-matching.js)|Hard|

solutions/0006-zigzag-conversion.js

@@ -0,0 +1,30 @@
+/**
+ * 6. ZigZag Conversion
+ * https://leetcode.com/problems/zigzag-conversion/
+ * Difficulty: Medium
+ *
+ * The string `"PAYPALISHIRING"` is written in a zigzag pattern on a given
+ * number of rows like this: (you may want to display this pattern in a
+ * fixed font for better legibility)
+ *
+ * > P   A   H   N
+ * > A P L S I I G
+ * > Y   I   R
+ *
+ * And then read line by line: `"PAHNAPLSIIGYIR"`
+ */
+
+/**
+ * @param {string} s
+ * @param {number} numRows
+ * @return {string}
+ */
+var convert = function(s, numRows) {
+  const order = [...new Array(numRows).keys()];
+  order.push(...order.slice(1, -1).reverse());
+
+  const rows = new Array(numRows).fill('');
+  [...s].forEach((c, i) => (rows[order[i % order.length]] += c));
+
+  return rows.join('');
+};