Leetcode subarray sum equals k

arrays.md

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+# Arrays
+
++ [Subarray Sum Equals K](#subarray-sum-equals-k)
+
+## Subarray sum equals k
+
+https://leetcode.com/problems/subarray-sum-equals-k/
+
+```python
+from collections import defaultdict
+
+
+class Solution(object):
+    def subarraySum(self, nums, k):
+        """
+        :type nums: List[int]
+        :type k: int
+        :rtype: int
+        """
+
+        _list, _dict, sums_count = [0] + [sum(nums[:index + 1]) for index in range(len(nums))], defaultdict(int), 0
+        for i in range(len(nums)):
+            _dict[_list[i]] += 1
+            sums_count += _dict[_list[i + 1] - k]
+        return sums_count
+
+```