Added Sliding Window folder with problems

Implementing Sliding Window/Max_Sum_Subarray.java

@@ -0,0 +1,29 @@
+import java.util.Scanner;
+public class Max_Sum_Subarray{
+    public static void main(String[] args) {
+        Scanner in = new Scanner(System.in);
+        int k = in.nextInt(); //window size
+        int n = in.nextInt(); //limit of array
+        int[] arr = new int[n];
+            for(int i=0;i<n;i++){
+            arr[i] = in.nextInt();
+        }
+        int j=0;
+        int i=0;
+        int sum=0;
+        int maxSum = Integer.MIN_VALUE;
+        while(j<arr.length){
+            sum+=arr[j];
+            if(j-i+1<k){
+                j++;
+            }
+            else if(j-i+1==k){
+                maxSum=Math.max(maxSum,sum);
+                sum-=arr[i];
+                i++;
+                j++;
+            }
+        }
+        System.out.println(maxSum);
+    }
+}