Add solution #413

Author: JoshCrozier

README.md

@@ -329,6 +329,7 @@
 409|[Longest Palindrome](./0409-longest-palindrome.js)|Easy|
 410|[Split Array Largest Sum](./0410-split-array-largest-sum.js)|Hard|
 412|[Fizz Buzz](./0412-fizz-buzz.js)|Easy|
+413|[Arithmetic Slices](./0413-arithmetic-slices.js)|Medium|
 414|[Third Maximum Number](./0414-third-maximum-number.js)|Easy|
 415|[Add Strings](./0415-add-strings.js)|Easy|
 416|[Partition Equal Subset Sum](./0416-partition-equal-subset-sum.js)|Medium|

solutions/0413-arithmetic-slices.js

@@ -0,0 +1,34 @@
+/**
+ * 413. Arithmetic Slices
+ * https://leetcode.com/problems/arithmetic-slices/
+ * Difficulty: Medium
+ *
+ * An integer array is called arithmetic if it consists of at least three elements and if
+ * the difference between any two consecutive elements is the same.
+ *
+ * For example, [1,3,5,7,9], [7,7,7,7], and [3,-1,-5,-9] are arithmetic sequences.
+ *
+ * Given an integer array nums, return the number of arithmetic subarrays of nums.
+ *
+ * A subarray is a contiguous subsequence of the array.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var numberOfArithmeticSlices = function(nums) {
+  if (nums.length < 3) return 0;
+  let result = 0;
+
+  for (let i = 2, value = 0; i < nums.length; i++) {
+    if (nums[i] - nums[i - 1] === nums[i - 1] - nums[i - 2]) {
+      value++;
+      result += value;
+    } else {
+      value = 0;
+    }
+  }
+
+  return result;
+};