day 16 solution in java

solutions/day16/solution_java.java

@@ -0,0 +1,39 @@
+import java.util.PriorityQueue;
+
+class Solution {
+    public String longestDiverseString(int a, int b, int c) {
+        // Priority queue to store the characters and their counts.
+        PriorityQueue<int[]> pq = new PriorityQueue<>((x, y) -> y[0] - x[0]);
+        if (a > 0) pq.offer(new int[]{a, 'a'});
+        if (b > 0) pq.offer(new int[]{b, 'b'});
+        if (c > 0) pq.offer(new int[]{c, 'c'});
+
+        StringBuilder result = new StringBuilder();
+
+        while (!pq.isEmpty()) {
+            int[] first = pq.poll();
+
+            // Check if last two characters are the same.
+            if (result.length() >= 2 && result.charAt(result.length() - 1) == first[1] &&
+                result.charAt(result.length() - 2) == first[1]) {
+
+                if (pq.isEmpty()) break;  // No more valid characters.
+
+                // Pick the second character.
+                int[] second = pq.poll();
+                result.append((char) second[1]);
+                second[0]--;
+
+                if (second[0] > 0) pq.offer(second);
+                pq.offer(first);
+            } else {
+                result.append((char) first[1]);
+                first[0]--;
+
+                if (first[0] > 0) pq.offer(first);
+            }
+        }
+
+        return result.toString();
+    }
+}