Add solution #560

Author: JoshCrozier

README.md

@@ -322,6 +322,7 @@
 547|[Number of Provinces](./0547-number-of-provinces.js)|Medium|
 551|[Student Attendance Record I](./0551-student-attendance-record-i.js)|Easy|
 557|[Reverse Words in a String III](./0557-reverse-words-in-a-string-iii.js)|Easy|
+560|[Subarray Sum Equals K](./0560-subarray-sum-equals-k.js)|Medium|
 563|[Binary Tree Tilt](./0563-binary-tree-tilt.js)|Easy|
 565|[Array Nesting](./0565-array-nesting.js)|Medium|
 566|[Reshape the Matrix](./0566-reshape-the-matrix.js)|Easy|

solutions/0560-subarray-sum-equals-k.js

@@ -0,0 +1,28 @@
+/**
+ * 560. Subarray Sum Equals K
+ * https://leetcode.com/problems/subarray-sum-equals-k/
+ * Difficulty: Medium
+ *
+ * Given an array of integers nums and an integer k, return the total number of subarrays
+ * whose sum equals to k.
+ *
+ * A subarray is a contiguous non-empty sequence of elements within an array.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var subarraySum = function(nums, k) {
+  const map = new Map([[0, 1]]);
+  let result = 0;
+
+  for (let i = 0, count = 0; i < nums.length; i++) {
+    count += nums[i];
+    result += map.get(count - k) ?? 0;
+    map.set(count, (map.get(count) ?? 0) + 1);
+  }
+
+  return result;
+};