Six Degrees of Collusion - Fraud Ring Size

Problem: Fraud Ring Size Direct device sharing is not enough to detect sophisticated fraud rings. Each log now contains a user, a device, and a credit-card hash: user_id,device_id,credit_card Two users are connected if they share either the same device_id or the same credit_card. Connectivity is transitive: if A shares a device with B, and B shares a card with C, then A, B, and C are in the same Fraud Ring. Given target_user, return the number of unique users in the Fraud Ring containing the target user, including the target user. If the target never appears, return 0. Input Format n transaction_1 transaction_2 ... transaction_n target_user Output Format Print one integer: the number of unique users in the connected component containing the target user. Constraints 0 <= n <= 2 * 10^5 All fields are non-empty strings without commas A user may appear multiple times with different devices or cards Connections may be chained through identifiers of arbitrary length Example Input 5 Alice,D1,CC1 Bob,D1,CC2 Charlie,D2,CC2 David,D3,CC3 Eve,D3,CC4 Alice Output 3