From 5b26d4e92996be1c8e7cb8afbc899dd54588d275 Mon Sep 17 00:00:00 2001
From: chayan das <dasshuvo817@gmail.com>
Date: Tue, 9 Dec 2025 14:33:05 +0530
Subject: [PATCH] Create 3583. Count Special Triplets

---
 3583. Count Special Triplets | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 3583. Count Special Triplets

diff --git a/3583. Count Special Triplets b/3583. Count Special Triplets
new file mode 100644
index 0000000..edf625c
--- /dev/null
+++ b/3583. Count Special Triplets	
@@ -0,0 +1,18 @@
+class Solution {
+public:
+    int specialTriplets(vector<int>& nums) {
+        const int n = 100001, mod = 1000000007;
+        long ans = 0;
+        int hash[n], prev[n];
+        for(int i = 0; i < n; i++) hash[i] = prev[i] = 0;
+        for(int i = 0; i < nums.size(); i++) hash[nums[i]]++;
+        for(int i = 1; i < nums.size() - 1; i++) {
+            prev[nums[i - 1]]++;
+            int j = nums[i], k = 2*j;
+            if(k < n) {
+                ans += (long)prev[k] * (hash[k] - prev[k] - (j == 0));
+            }
+        }
+        return ans % mod;
+    }
+};