Final Implementation

problem1.py

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+## Problem1 (https://leetcode.com/problems/subarray-sum-equals-k/)
+
+class Solution:
+    def subarraySum(self, nums: List[int], k: int) -> int:
+        r_sum = 0 
+        hm = {
+            0:1
+        }
+        count = 0
+        for num in nums:
+            r_sum += num 
+            comp = r_sum - k
+            if comp in hm:
+                count+=hm[comp]
+            if r_sum in hm:
+                hm[r_sum]+=1
+            else:
+                hm[r_sum]=1
+        return count

problem2.py

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+## Problem2 (https://leetcode.com/problems/contiguous-array/)
+
+class Solution:
+    def findMaxLength(self, nums: List[int]) -> int:
+        r_sum = 0
+        max_length = 0 
+        my_map = {
+            0:-1
+        }
+        for i in range(len(nums)):
+            if nums[i] == 0:
+                r_sum-=1 
+            else:
+                r_sum+=1 
+
+            if r_sum in my_map:
+                max_length = max(max_length,i-my_map[r_sum])
+            else:
+                my_map[r_sum] = i 
+        return max_length

problem3.py

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+## Problem3 (https://leetcode.com/problems/longest-palindrome)
+
+class Solution:
+    def longestPalindrome(self, s: str) -> int:
+        my_set = set()
+        count = 0
+        for i in s:
+            if i in my_set:
+                count+=2
+                my_set.remove(i)
+            else:
+                my_set.add(i)
+        if len(my_set) > 0:
+            return count+1
+        return count