Add solution #930

Author: JoshCrozier

README.md

@@ -739,6 +739,7 @@
 927|[Three Equal Parts](./solutions/0927-three-equal-parts.js)|Hard|
 928|[Minimize Malware Spread II](./solutions/0928-minimize-malware-spread-ii.js)|Hard|
 929|[Unique Email Addresses](./solutions/0929-unique-email-addresses.js)|Easy|
+930|[Binary Subarrays With Sum](./solutions/0930-binary-subarrays-with-sum.js)|Medium|
 933|[Number of Recent Calls](./solutions/0933-number-of-recent-calls.js)|Easy|
 937|[Reorder Data in Log Files](./solutions/0937-reorder-data-in-log-files.js)|Medium|
 966|[Vowel Spellchecker](./solutions/0966-vowel-spellchecker.js)|Medium|

solutions/0930-binary-subarrays-with-sum.js

@@ -0,0 +1,29 @@
+/**
+ * 930. Binary Subarrays With Sum
+ * https://leetcode.com/problems/binary-subarrays-with-sum/
+ * Difficulty: Medium
+ *
+ * Given a binary array nums and an integer goal, return the number of non-empty subarrays
+ * with a sum goal.
+ *
+ * A subarray is a contiguous part of the array.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} goal
+ * @return {number}
+ */
+var numSubarraysWithSum = function(nums, goal) {
+  const map = new Map([[0, 1]]);
+  let result = 0;
+  let sum = 0;
+
+  for (const num of nums) {
+    sum += num;
+    result += map.get(sum - goal) || 0;
+    map.set(sum, (map.get(sum) || 0) + 1);
+  }
+
+  return result;
+};