Create Count Special Triplets.java

varunu28 · web-flow · commit a802621ebacb · 2025-06-16T19:45:48.000-05:00
diff --git a/Medium/Count Special Triplets.java b/Medium/Count Special Triplets.java
@@ -0,0 +1,21 @@
+class Solution {
+
+    private static final int MOD = 1_000_000_007;
+
+    public int specialTriplets(int[] nums) {
+        int result = 0;
+        Map<Integer, Integer> leftFrequency = new HashMap<>();
+        Map<Integer, Integer> rightFrequency = new HashMap<>();
+        for (int num : nums) {
+            rightFrequency.put(num, rightFrequency.getOrDefault(num, 0) + 1);
+        }
+        for (int num : nums) {
+            rightFrequency.put(num, rightFrequency.getOrDefault(num, 0) - 1);
+            int leftMultiple = leftFrequency.getOrDefault(num * 2, 0);
+            int rightMultiple = rightFrequency.getOrDefault(num * 2, 0);
+            result = (int) ((result + 1L * leftMultiple * rightMultiple) % MOD);
+            leftFrequency.put(num, leftFrequency.getOrDefault(num, 0) + 1);
+        }        
+        return result;
+    }
+}
