diff --git a/Subarray Sum Equals K b/Subarray Sum Equals K
new file mode 100644
index 00000000..73ccef55
--- /dev/null
+++ b/Subarray Sum Equals K	
@@ -0,0 +1,20 @@
+class Solution {
+public:
+    int subarraySum(vector<int>& nums, int k) {
+        unordered_map<int, int> um;
+        int sum = 0, ans = 0; 
+        um[sum]++;
+        
+        for (int i=0; i<nums.size();i++)
+        {
+            sum += nums[i];
+            
+            if (um.find(sum-k) != um.end())
+                ans+=um[sum-k];
+
+            um[sum]++;
+        }
+
+        return ans;
+    }
+};
diff --git a/longestPalindrome.cpp b/longestPalindrome.cpp
new file mode 100644
index 00000000..668022bf
--- /dev/null
+++ b/longestPalindrome.cpp
@@ -0,0 +1,30 @@
+// Time complexity :  O(n)
+// Space complexity : O(n) where n is the length of the string
+class Solution {
+public:
+    int longestPalindrome(string s) {
+        unordered_map<char, int> um;
+        int result=0;
+
+        for (int i=0;i<s.length();i++)
+        {
+            um[s[i]]++;
+            if (um[s[i]] == 2)
+            {
+                result+=2;
+                um.erase(s[i]);
+            }
+        }
+
+        for (auto x: um)
+        {
+            if (x.second % 2 != 0)
+            {
+                result++;
+                break;
+            }
+        }
+
+        return result;
+    }
+};