Add solution #1524

Author: JoshCrozier

README.md

@@ -557,6 +557,7 @@
 1507|[Reformat Date](./1507-reformat-date.js)|Easy|
 1512|[Number of Good Pairs](./1512-number-of-good-pairs.js)|Easy|
 1519|[Number of Nodes in the Sub-Tree With the Same Label](./1519-number-of-nodes-in-the-sub-tree-with-the-same-label.js)|Medium|
+1524|[Number of Sub-arrays With Odd Sum](./1524-number-of-sub-arrays-with-odd-sum.js)|Medium|
 1528|[Shuffle String](./1528-shuffle-string.js)|Easy|
 1535|[Find the Winner of an Array Game](./1535-find-the-winner-of-an-array-game.js)|Medium|
 1550|[Three Consecutive Odds](./1550-three-consecutive-odds.js)|Easy|

solutions/1524-number-of-sub-arrays-with-odd-sum.js

@@ -0,0 +1,26 @@
+/**
+ * 1524. Number of Sub-arrays With Odd Sum
+ * https://leetcode.com/problems/number-of-sub-arrays-with-odd-sum/
+ * Difficulty: Medium
+ *
+ * Given an array of integers arr, return the number of subarrays with an odd sum.
+ *
+ * Since the answer can be very large, return it modulo 109 + 7.
+ */
+
+/**
+ * @param {number[]} arr
+ * @return {number}
+ */
+var numOfSubarrays = function(arr) {
+  let even = 0;
+  let odd = 0;
+
+  for (let i = 0, total = 0; i < arr.length; i++) {
+    total += arr[i];
+    odd += +(total % 2 === 1);
+    even += +(total % 2 === 0);
+  }
+
+  return (odd * even + odd) % (1e9 + 7);
+};