Add Longest Subarray with Sum Less Than or Equal to K algorithm and tests

Author: Chiefpatwal

src/main/java/com/thealgorithms/slidingwindow/LongestSubarrayWithSumLessOrEqualToK.java

@@ -0,0 +1,49 @@
+package com.thealgorithms.slidingwindow;
+
+/**
+ * The Longest Subarray with Sum Less Than or Equal to K algorithm finds the length of the longest
+ * subarray with a sum that does not exceed a given value `k`.
+ *
+ * <p>
+ * Worst-case performance O(n)
+ * Best-case performance O(n)
+ * Average performance O(n)
+ * Worst-case space complexity O(1)
+ *
+ * @author  (https://github.com/Chiefpatwal)
+ */
+public final class LongestSubarrayWithSumLessOrEqualToK {
+
+    // Prevent instantiation
+    private LongestSubarrayWithSumLessOrEqualToK() {
+    }
+
+    /**
+     * Finds the length of the longest subarray with a sum less than or equal to a given value.
+     *
+     * @param nums The input array of integers
+     * @param k The maximum allowed sum for the subarray
+     * @return The length of the longest subarray with sum <= k
+     */
+    public static int longestSubarrayWithSumLEK(int[] nums, int k) {
+        int maxLength = 0;
+        int currentSum = 0;
+        int left = 0;
+
+        // Expand the window by moving `right`
+        for (int right = 0; right < nums.length; right++) {
+            currentSum += nums[right];
+
+            // Shrink the window from the left if `currentSum` exceeds `k`
+            while (currentSum > k && left <= right) {
+                currentSum -= nums[left];
+                left++;
+            }
+
+            // Update the maximum length if the current window is valid
+            maxLength = Math.max(maxLength, right - left + 1);
+        }
+
+        return maxLength;
+    }
+}

src/test/java/com/thealgorithms/slidingwindow/LongestSubarrayWithSumLessOrEqualToKTest.java

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+package com.thealgorithms.slidingwindow;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for the LongestSubarrayWithSumLessOrEqualToK class.
+ *
+ * @author  (https://github.com/Chiefpatwal)
+ */
+public class LongestSubarrayWithSumLessOrEqualToKTest {
+
+    @Test
+    public void testLongestSubarrayWithSumLEK() {
+        // Test cases for the longestSubarrayWithSumLEK method
+        assertEquals(3, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[]{1, 2, 3, 4, 5}, 11));
+        assertEquals(2, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[]{2, 1, 1, 1, 1}, 3));
+        assertEquals(5, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[]{1, 2, 3, 4, 5}, 15));
+        assertEquals(0, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[]{10, 20, 30}, 5));
+        assertEquals(4, LongestSubarrayWithSumLessOrEqualToK.longestSubarrayWithSumLEK(new int[]{3, 1, 2, 1, 1}, 5));
+    }
+}