From bc7276acc1346297541d204ed3a58930b6aa97f3 Mon Sep 17 00:00:00 2001
From: sandy7907 <nagasai.guttikonda@gmail.com>
Date: Sat, 14 Feb 2026 21:36:47 -0500
Subject: [PATCH 1/2] S30 FAANMG Problem #19 | Longest Palindrome

---
 LongestPalindrome.java | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 LongestPalindrome.java

diff --git a/LongestPalindrome.java b/LongestPalindrome.java
new file mode 100644
index 00000000..91eb48e2
--- /dev/null
+++ b/LongestPalindrome.java
@@ -0,0 +1,18 @@
+class LongestPalindrome {
+    public int longestPalindrome(String s) {
+
+        Set<Character> dict = new HashSet<>();
+        int count = 0;
+
+        for(char c : s.toCharArray()) {
+            if(dict.contains(c)) {
+                count += 2;
+                dict.remove(c);
+            } else {
+                dict.add(c);
+            }
+        }
+
+        return dict.size() > 0 ? count + 1 : count;
+    }
+}
\ No newline at end of file

From c19395cd8293efa09fbff4f7fc9b80920f89a2d7 Mon Sep 17 00:00:00 2001
From: sandy7907 <nagasai.guttikonda@gmail.com>
Date: Sun, 15 Feb 2026 00:36:55 -0500
Subject: [PATCH 2/2] S30 FAANMG Problem #18, 20 | Hashing 2 Problems

---
 ContiguousArray.java | 20 ++++++++++++++++++++
 README.md            |  6 +++---
 SubArraySum.java     | 21 +++++++++++++++++++++
 3 files changed, 44 insertions(+), 3 deletions(-)
 create mode 100644 ContiguousArray.java
 create mode 100644 SubArraySum.java

diff --git a/ContiguousArray.java b/ContiguousArray.java
new file mode 100644
index 00000000..9a1e1351
--- /dev/null
+++ b/ContiguousArray.java
@@ -0,0 +1,20 @@
+class ContiguousArray {
+    public int findMaxLength(int[] nums) {
+
+        HashMap<Integer, Integer> rSum = new HashMap<>();
+        rSum.put(0, -1);
+        int sum = 0, max = 0;
+        for(int i = 0; i < nums.length; i++) {
+            sum += nums[i] == 0 ? -1 : 1;
+
+            if(rSum.containsKey(sum)) {
+                max = Math.max(max, i - rSum.get(sum));
+            } else {
+                rSum.put(sum, i);
+            }
+        }
+
+        return max;
+
+    }
+}
\ No newline at end of file
diff --git a/README.md b/README.md
index 039a4259..2c1ad367 100644
--- a/README.md
+++ b/README.md
@@ -3,10 +3,10 @@
 Explain your approach in **three sentences only** at top of your code
 
 
-## Problem1 (https://leetcode.com/problems/subarray-sum-equals-k/)
+## Problem1 SubArraySum (https://leetcode.com/problems/subarray-sum-equals-k/)
 
 
-## Problem2 (https://leetcode.com/problems/contiguous-array/)
+## Problem2 ContiguousArray (https://leetcode.com/problems/contiguous-array/)
 
 
-## Problem3 (https://leetcode.com/problems/longest-palindrome)
+## Problem3 LongestPalindrome (https://leetcode.com/problems/longest-palindrome)
diff --git a/SubArraySum.java b/SubArraySum.java
new file mode 100644
index 00000000..a3a5745d
--- /dev/null
+++ b/SubArraySum.java
@@ -0,0 +1,21 @@
+// Using RSum to calculate the sum at that Index
+// Add a default entry in the map with [0, 1] to make sure if the comp(rSum -k) is 0 then the array until that elemnt will be 1 sub array
+// if different between running sum to k is available in the map then a sub array is found
+// insert element in the map based on running sum and counter
+class SubArraySum {
+    public int subarraySum(int[] nums, int k) {
+        HashMap<Integer, Integer> rSumCounterMap = new HashMap<>();
+        int rSum = 0;
+        rSumCounterMap.put(0, 1);
+        int count = 0;
+        for(int i = 0; i< nums.length;i++) {
+            rSum += nums[i];
+
+            if(rSumCounterMap.containsKey(rSum - k)) {
+                count += rSumCounterMap.get(rSum - k);
+            }
+            rSumCounterMap.merge(rSum, 1, Integer::sum);
+        }
+        return count;
+    }
+}
\ No newline at end of file