Added Maximum Sliding Window algorithm using deque for efficient O(n) solution.

src/main/java/com/thealgorithms/others/MaximumSlidingWindow.java

@@ -0,0 +1,69 @@
+package com.thealgorithms.others;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+/**
+ * Maximum Sliding Window Algorithm
+ *
+ * This algorithm finds the maximum element in each sliding window of size k
+ * in a given array of integers. It uses a deque (double-ended queue) to
+ * efficiently keep track of potential maximum values in the current window.
+ *
+ * Time Complexity: O(n), where n is the number of elements in the input array
+ * Space Complexity: O(k), where k is the size of the sliding window
+ */
+
+public class MaximumSlidingWindow {
+
+    /**
+     * Finds the maximum values in each sliding window of size k.
+     *
+     * @param nums The input array of integers
+     * @param windowSize The size of the sliding window
+     * @return An array of integers representing the maximums in each window
+     */
+    public int[] maxSlidingWindow(int[] nums, int windowSize) {
+        if (nums == null || nums.length == 0 || windowSize <= 0 || windowSize > nums.length) {
+            return new int[0]; // Handle edge cases
+        }
+
+        int[] result = new int[nums.length - windowSize + 1];
+        Deque<Integer> deque = new ArrayDeque<>();
+
+        for (int currentIndex = 0; currentIndex < nums.length; currentIndex++) {
+
+            // Remove the first element if it's outside the current window
+            if (!deque.isEmpty() && deque.peekFirst() == currentIndex - windowSize) {
+                deque.pollFirst();
+            }
+
+            // Remove all elements smaller than the current element from the end
+            while (!deque.isEmpty() && nums[deque.peekLast()] < nums[currentIndex]) {
+                deque.pollLast();
+            }
+
+            // Add the current element's index to the deque
+            deque.offerLast(currentIndex);
+
+            // If we have processed at least k elements, add to result
+            if (currentIndex >= windowSize - 1) {
+                result[currentIndex - windowSize + 1] = nums[deque.peekFirst()];
+            }
+        }
+        return result;
+    }
+    public static void main(String[] args) {
+        MaximumSlidingWindow msw = new MaximumSlidingWindow();
+        int[] nums = {1, 3, -1, -3, 5, 3, 6, 7};
+        int k = 3;
+
+        // Calculate the maximum sliding window
+        int[] result = msw.maxSlidingWindow(nums, k);
+
+        // Print the result
+        for (int num : result) {
+            System.out.print(num + " ");
+        }
+    }
+}