diff --git a/Contiguous_array.py b/Contiguous_array.py
new file mode 100644
index 00000000..d6a5ed9c
--- /dev/null
+++ b/Contiguous_array.py
@@ -0,0 +1,20 @@
+class Solution:
+    def findMaxLength(self, nums: List[int]) -> int:
+
+        running_sum=0
+        map={}
+        max_length=0
+
+        map[0]=-1
+
+        for i in range(len(nums)):
+            if nums[i]==0:
+                running_sum=running_sum-1
+            else:
+                running_sum+=1
+            if running_sum not in map:
+                map[running_sum]=i
+            else:
+                max_length=max(max_length, i-map[running_sum])
+        return max_length
+        
\ No newline at end of file
diff --git a/Longest_Palindrome.py b/Longest_Palindrome.py
new file mode 100644
index 00000000..3dd5af36
--- /dev/null
+++ b/Longest_Palindrome.py
@@ -0,0 +1,18 @@
+class Solution:
+    def longestPalindrome(self, s: str) -> int:
+
+        count=0
+        a_set=set()
+
+        for i in range(len(s)):
+            if s[i] not in a_set:
+                a_set.add(s[i])
+            else:
+                count=count+2
+                a_set.remove(s[i])
+        if len(a_set)>0:
+            return count+1
+        else:
+            return count
+
+        
\ No newline at end of file
diff --git a/subarray sum equals K.py b/subarray sum equals K.py
new file mode 100644
index 00000000..aab8167e
--- /dev/null
+++ b/subarray sum equals K.py	
@@ -0,0 +1,18 @@
+class Solution:
+    def subarraySum(self, nums: List[int], k: int) -> int:
+
+        running_sum=0
+
+        map={}
+        map[0]=1
+        count=0
+        for i in range(len(nums)):
+            running_sum+=nums[i]
+            if running_sum-k in map:
+                count=count+map[running_sum-k]
+            if running_sum not in map:
+                map[running_sum]=1
+            else:
+                map[running_sum]+=1
+            
+        return count
\ No newline at end of file