resolves problems

Author: Darshan-Baligeri

src/main/java/com/thealgorithms/shufflealogrithm/UniquePairShuffle.java

@@ -28,7 +28,7 @@ static List<int[]> pairShuffle(int[] array) {
         List<int[]> pairs = new ArrayList<>();
 
         // Handle edge case: If the array length is odd, pairing is not possible
-        if (array.length % 2 != 0) {
+        if (array.length < 2 || array.length % 2 != 0) {
             return pairs;
         }
 
@@ -40,18 +40,9 @@ static List<int[]> pairShuffle(int[] array) {
         // Shuffle elements to create random pairs
         Collections.shuffle(shuffledList);
 
-        // Form pairs from the shuffled elements, avoiding duplicate pairs
-        Set<String> uniquePairs = new HashSet<>();
+        // Form pairs from the shuffled elements
         for (int i = 0; i < shuffledList.size(); i += 2) {
-            int[] pair = new int[]{shuffledList.get(i), shuffledList.get(i + 1)};
-            String pairKey =
-                    Math.min(pair[0], pair[1]) + "-" + Math.max(pair[0], pair[1]);
-
-            // Ensure no repeated pairs
-            if (!uniquePairs.contains(pairKey)) {
-                pairs.add(pair);
-                uniquePairs.add(pairKey);
-            }
+            pairs.add(new int[]{shuffledList.get(i), shuffledList.get(i + 1)});
         }
 
         return pairs;

src/main/java/com/thealgorithms/shufflealogrithm/WeightedShuffle.java

@@ -33,9 +33,8 @@ static void weightedShuffle(int[] array, int[] weights) {
 
         Random random = new Random();
 
-        // Sort indices by weights in descending order with a random factor to break
-        // ties
-        Arrays.sort(indices, Comparator.<Integer>comparingInt(i->- weights[i])
+        // Sort indices by weights in descending order, prioritizing higher weights
+        Arrays.sort(indices, Comparator.comparingInt((Integer i)->- weights[i])
                 .thenComparingInt(i->random.nextInt()));
 
         int[] result = new int[array.length];