Merge branch 'master' into testing/AverageTest

Author: DenizAltunkapan

src/main/java/com/thealgorithms/maths/Convolution.java

@@ -23,24 +23,21 @@ public static double[] convolution(double[] a, double[] b) {
         double[] convolved = new double[a.length + b.length - 1];
 
         /*
-    The discrete convolution of two signals A and B is defined as:
-
-          A.length
-    C[i] = Σ (A[k]*B[i-k])
-          k=0
-
-    It's obvious that:  0 <= k <= A.length , 0 <= i <= A.length + B.length - 2  and  0 <= i-k <=
-    B.length - 1 From the last inequality we get that:  i - B.length + 1 <= k <= i and thus we get
-    the conditions below.
+         * Discrete convolution formula:
+         * C[i] = Σ A[k] * B[i - k]
+         * where k ranges over valid indices so that both A[k] and B[i-k] are in bounds.
          */
+
         for (int i = 0; i < convolved.length; i++) {
-            convolved[i] = 0;
-            int k = Math.max(i - b.length + 1, 0);
+            double sum = 0;
+            int kStart = Math.max(0, i - b.length + 1);
+            int kEnd = Math.min(i, a.length - 1);
 
-            while (k < i + 1 && k < a.length) {
-                convolved[i] += a[k] * b[i - k];
-                k++;
+            for (int k = kStart; k <= kEnd; k++) {
+                sum += a[k] * b[i - k];
             }
+
+            convolved[i] = sum;
         }
 
         return convolved;

src/main/java/com/thealgorithms/maths/Mode.java

@@ -3,46 +3,49 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
-/*
- * Find the mode of an array of numbers
- *
- * The mode of an array of numbers is the most frequently occurring number in the array,
- * or the most frequently occurring numbers if there are multiple numbers with the same frequency
+/**
+ * Utility class to calculate the mode(s) of an array of integers.
+ * <p>
+ * The mode of an array is the integer value(s) that occur most frequently.
+ * If multiple values have the same highest frequency, all such values are returned.
+ * </p>
  */
 public final class Mode {
     private Mode() {
     }
 
-    /*
-     * Find the mode of an array of integers
+    /**
+     * Computes the mode(s) of the specified array of integers.
+     * <p>
+     * If the input array is empty, this method returns {@code null}.
+     * If multiple numbers share the highest frequency, all are returned in the result array.
+     * </p>
      *
-     * @param numbers array of integers
-     * @return mode of the array
+     * @param numbers an array of integers to analyze
+     * @return an array containing the mode(s) of the input array, or {@code null} if the input is empty
      */
     public static int[] mode(final int[] numbers) {
         if (numbers.length == 0) {
             return null;
         }
 
-        HashMap<Integer, Integer> count = new HashMap<>();
+        Map<Integer, Integer> count = new HashMap<>();
 
         for (int num : numbers) {
-            if (count.containsKey(num)) {
-                count.put(num, count.get(num) + 1);
-            } else {
-                count.put(num, 1);
-            }
+            count.put(num, count.getOrDefault(num, 0) + 1);
         }
 
         int max = Collections.max(count.values());
-        ArrayList<Integer> modes = new ArrayList<>();
+        List<Integer> modes = new ArrayList<>();
 
         for (final var entry : count.entrySet()) {
             if (entry.getValue() == max) {
                 modes.add(entry.getKey());
             }
         }
-        return modes.stream().mapToInt(n -> n).toArray();
+        return modes.stream().mapToInt(Integer::intValue).toArray();
     }
 }