Update 560-subarray-sum-equals-k.js

Author: everthis

560-subarray-sum-equals-k.js

@@ -21,3 +21,26 @@ const subarraySum = function(nums, k) {
   }
   return totalNum
 }
+
+// another
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+const subarraySum = function (nums, k) {
+  const n = nums.length, hash = { 0: 1 }
+  let pre = 0
+  if (nums.length === 1) {
+    return nums[0] === k ? 1 : 0
+  }
+  let res = 0
+  for (let i = 0; i < n; i++) {
+    const cur = pre + nums[i]
+    if (hash[cur - k] != null) res += hash[cur - k]
+    hash[cur] = (hash[cur] || 0) + 1
+    pre = cur
+  }
+  return res
+}