Added maximum average of contiguous subarray with length k

Author: S-M-J-I

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

@@ -0,0 +1,53 @@
+package com.thealgorithms.others;
+
+/**
+ * References: https://www.geeksforgeeks.org/find-maximum-average-subarray-of-k-length/
+ *
+ * This algorithm involves computing the maximum average of sub arrays of a fixed size k from integers.
+ * This is a sliding window technique
+ * As we go through the array, we sum up the integers upto k.
+ * Once we do reach k initially, we average the numbers and compare it to the current maximum
+ * To move onto the next number, we subtract the number at the start of the window,
+ * and add the number at the end of the window
+ *
+ * @author S-M-J-I
+ */
+public class MaximumAverageOfContiguousSubArraysWithK {
+    public MaximumAverageOfContiguousSubArraysWithK() {
+    }
+
+    /**
+     * Finds the maximum average of a contiguous sub array of size K.
+     *
+     * @param k The size of the sub array.
+     * @param numbers The array from which sub arrays will be considered.
+     *
+     * @return The maximum average of the contiguous sub array of size K. If no such sub array exists, returns 0.
+     */
+    public double maxAverage(int k, int... numbers) {
+        // If there are no elements in the array
+        if (numbers.length == 0) {
+            // Return 0
+            return 0;
+        }
+        // If there is only one element, return that element
+        if (numbers.length == 1) {
+            return numbers[0];
+        }
+
+        double MAX = Integer.MIN_VALUE; // Keep track of the maximum average
+        double runningSum = 0; // Keep track of the running sum
+        // For all elements in the array
+        for(int i = 0; i < numbers.length; ++i) {
+            runningSum += numbers[i]; // Add the current element to the running sum
+            if (i >= k - 1) { // If we reach a minimum number of k elements
+                double div = runningSum / k; // Find the average
+                MAX = Math.max(div, MAX); // Compare and set the new maximum
+                runningSum -= numbers[i - (k - 1)]; // Subtract the first element in the window
+            }
+        }
+
+        // Return the maximum average
+        return MAX;
+    }
+}

src/test/java/com/thealgorithms/others/MaximumAverageOfContiguousSubArraysWithKTest.java

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+package com.thealgorithms.others;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class MaximumAverageOfContiguousSubArraysWithKTest {
+
+    private MaximumAverageOfContiguousSubArraysWithK solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new MaximumAverageOfContiguousSubArraysWithK();
+    }
+
+    @Test
+    public void testCaseOneNormal() {
+        int[] numbers = new int[] {1,12,-5,-6,50,3};
+        int k = 4;
+        double answer = 12.75;
+        double result = solution.maxAverage(k,numbers);
+        assertEquals(answer, result);
+    }
+
+    @Test
+    public void testCaseTwoOneElement() {
+        int[] numbers = new int[] {5};
+        int k = 1;
+        double answer = 5.00;
+        double result = solution.maxAverage(k,numbers);
+        assertEquals(answer, result);
+    }
+
+    @Test
+    public void testCaseThreeNegativeElement() {
+        int[] numbers = new int[] {-1};
+        int k = 1;
+        double answer = -1.00;
+        double result = solution.maxAverage(k,numbers);
+        assertEquals(answer, result);
+    }
+
+    @Test
+    public void testCaseFourNearLimit() {
+        int[] numbers = new int[] {
+                8860,-853,6534,4477,-4589,8646,-6155,-5577,-1656,-5779,-2619,-8604,-1358,-8009,
+                4983,7063,3104,-1560,4080,2763,5616,-2375,2848,1394,-7173,-5225,-8244,-809,8025,
+                -4072,-4391,-9579,1407,6700,2421,-6685,5481,-1732,-8892,-6645,3077,3287,-4149,8701,
+                -4393,-9070,-1777,2237,-3253,-506,-4931,-7366,-8132,5406,-6300,-275,-1908,67,3569,1433,
+                -7262,-437,8303,4498,-379,3054,-6285,4203,6908,4433,3077,2288,9733,-8067,3007,9725,9669,
+                1362,-2561,-4225,5442,-9006,-429,160,-9234,-4444,3586,-5711,-9506,-79,-4418,-4348,-5891
+        };
+        int k = 93;
+        double answer = -594.58065;
+        double result = solution.maxAverage(k,numbers);
+        assertEquals(answer, result);
+    }
+}