Add solution #1424

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,297 LeetCode solutions in JavaScript
+# 1,298 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1089,6 +1089,7 @@
 1420|[Build Array Where You Can Find The Maximum Exactly K Comparisons](./solutions/1420-build-array-where-you-can-find-the-maximum-exactly-k-comparisons.js)|Hard|
 1422|[Maximum Score After Splitting a String](./solutions/1422-maximum-score-after-splitting-a-string.js)|Easy|
 1423|[Maximum Points You Can Obtain from Cards](./solutions/1423-maximum-points-you-can-obtain-from-cards.js)|Medium|
+1424|[Diagonal Traverse II](./solutions/1424-diagonal-traverse-ii.js)|Medium|
 1431|[Kids With the Greatest Number of Candies](./solutions/1431-kids-with-the-greatest-number-of-candies.js)|Easy|
 1436|[Destination City](./solutions/1436-destination-city.js)|Easy|
 1437|[Check If All 1's Are at Least Length K Places Away](./solutions/1437-check-if-all-1s-are-at-least-length-k-places-away.js)|Easy|

solutions/1424-diagonal-traverse-ii.js

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+/**
+ * 1424. Diagonal Traverse II
+ * https://leetcode.com/problems/diagonal-traverse-ii/
+ * Difficulty: Medium
+ *
+ * Given a 2D integer array nums, return all elements of nums in diagonal order as shown
+ * in the below images.
+ */
+
+/**
+ * @param {number[][]} nums
+ * @return {number[]}
+ */
+var findDiagonalOrder = function(nums) {
+  const diagonalGroups = [];
+
+  for (let row = 0; row < nums.length; row++) {
+    for (let col = 0; col < nums[row].length; col++) {
+      const sum = row + col;
+      if (!diagonalGroups[sum]) {
+        diagonalGroups[sum] = [];
+      }
+      diagonalGroups[sum].push(nums[row][col]);
+    }
+  }
+
+  const result = [];
+  for (const group of diagonalGroups) {
+    if (group) {
+      result.push(...group.reverse());
+    }
+  }
+
+  return result;
+};