Given an array of integers and an integer k, you need to find the total number of continuous subarrays whose sum equals to k.
Example 1:
Input:nums = [1,1,1], k = 2
Output: 2
Note:
The length of the array is in range [1, 20,000].
The range of numbers in the array is [-1000, 1000] and the range of the integer k is [-1e7, 1e7].
class Solution:
     def subarraySum(self, nums, k):
         """
         :type nums: List[int]
         :type k: int
         :rtype: int
         """
         l_nums = len(nums)
         c = 0
         state = dict()
         state[0] = 1
         sum = 0
         
         for idx in range(0, l_nums):
             sum += nums[idx]
             if((sum - k) in state):
                 c += state[sum - k]
             state[sum] = (state[sum] if sum in state else 0) + 1
         return c
     

class Solution:
     def subarraySum(self, nums, k):
         """
         :type nums: List[int]
         :type k: int
         :rtype: int
         """
         l_nums = len(nums)
         c = 0
         state = dict()
         state[0] = 1
         sum = 0
         
         for idx in range(0, l_nums):
             sum += nums[idx]
             if((sum - k) in state):
                 c += state[sum - k]
             state[sum] = (state[sum] if sum in state else 0) + 1
         return c
     
