Implement sliding window algorithms for fixed and dynamic sizes with tests (#1765)

* feat: implement sliding window algorithms for fixed and dynamic sizes with tests

* update directory file for sliding windows

Sliding-Windows/test/LongestSubarrayWithSumAtMost.test.js

@@ -0,0 +1,24 @@
+import { longestSubarrayWithSumAtMost } from '../LongestSubarrayWithSumAtMost'
+
+describe('Dynamic-size Sliding Window - longestSubarrayWithSumAtMost', () => {
+  it('should return the longest subarray length with sum <= target', () => {
+    const arr = [1, 2, 3, 4, 5]
+    const target = 7
+    const result = longestSubarrayWithSumAtMost(arr, target)
+    expect(result).toBe(3)
+  })
+
+  it('should return the full array length if the entire sum is within the target', () => {
+    const arr = [1, 1, 1, 1]
+    const target = 4
+    const result = longestSubarrayWithSumAtMost(arr, target)
+    expect(result).toBe(4)
+  })
+
+  it('should return 0 if no subarray meets the sum condition', () => {
+    const arr = [5, 6, 7]
+    const target = 3
+    const result = longestSubarrayWithSumAtMost(arr, target)
+    expect(result).toBe(0)
+  })
+})

Sliding-Windows/test/MaxSumSubarrayFixed.test.js

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+import { maxSumSubarrayFixed } from '../MaxSumSubarrayFixed'
+
+describe('Fixed-size Sliding Window - maxSumSubarrayFixed', () => {
+  it('should return the maximum sum of a subarray of size k', () => {
+    const arr = [2, 1, 5, 1, 3, 2]
+    const k = 3
+    const result = maxSumSubarrayFixed(arr, k)
+    expect(result).toBe(9)
+  })
+
+  it('should throw a RangeError if k is larger than the array length', () => {
+    const arr = [2, 1, 5]
+    const k = 4
+    expect(() => maxSumSubarrayFixed(arr, k)).toThrow(RangeError)
+  })
+
+  it('should throw a RangeError if k is less than 1', () => {
+    const arr = [2, 1, 5]
+    const k = 0
+    expect(() => maxSumSubarrayFixed(arr, k)).toThrow(RangeError)
+  })
+})