Add solution #422

Author: JoshCrozier

README.md

@@ -410,6 +410,7 @@
 419|[Battleships in a Board](./solutions/0419-battleships-in-a-board.js)|Medium|
 420|[Strong Password Checker](./solutions/0420-strong-password-checker.js)|Hard|
 421|[Maximum XOR of Two Numbers in an Array](./solutions/0421-maximum-xor-of-two-numbers-in-an-array.js)|Medium|
+422|[Valid Word Square](./solutions/0422-valid-word-square.js)|Easy|
 423|[Reconstruct Original Digits from English](./solutions/0423-reconstruct-original-digits-from-english.js)|Medium|
 424|[Longest Repeating Character Replacement](./solutions/0424-longest-repeating-character-replacement.js)|Medium|
 427|[Construct Quad Tree](./solutions/0427-construct-quad-tree.js)|Medium|

solutions/0422-valid-word-square.js

@@ -0,0 +1,30 @@
+/**
+ * 422. Valid Word Square
+ * https://leetcode.com/problems/valid-word-square/
+ * Difficulty: Easy
+ *
+ * Given an array of strings words, return true if it forms a valid word square.
+ *
+ * A sequence of strings forms a valid word square if the kth row and column read the same
+ * string, where 0 <= k < max(numRows, numColumns).
+ */
+
+/**
+ * @param {string[]} words
+ * @return {boolean}
+ */
+var validWordSquare = function(words) {
+  const rowCount = words.length;
+
+  for (let rowIndex = 0; rowIndex < rowCount; rowIndex++) {
+    const row = words[rowIndex];
+    for (let colIndex = 0; colIndex < row.length; colIndex++) {
+      if (colIndex >= rowCount || rowIndex >= words[colIndex].length
+          || row[colIndex] !== words[colIndex][rowIndex]) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+};