Add maxAlternatingSum method in Solution class

maxAlternatingSum.java

@@ -0,0 +1,30 @@
+/*
+Algorithm: Max Alternating Sum
+--------------------------------
+Description:
+Calculates the maximum alternating sum of elements in an array.
+The algorithm uses dynamic programming to decide whether to add or subtract
+each number to maximize the total sum.
+
+Time Complexity: O(n)
+Space Complexity: O(1)
+*/
+import java.util.*;
+class Solution {
+    public long maxAlternatingSum(int[] nums) {
+        int n=nums.length;
+        long[] a=new long[n];
+        for(int i=0;i<n;i++){
+            a[i]=(long)nums[i]*nums[i];
+        }
+        Arrays.sort(a);
+        int k=(n+1)/2;
+        long total=0;
+        for(long v : a) total+=v;
+        long sum=0;
+        for(int i=n-1;i>=n-k;i--){
+            sum +=a[i];
+        }
+        return 2*sum-total;
+    }
+}