Optimal Account Balancing

Given a list of transactions, where transactions[i] = [from_i, to_i, amount_i] means that person from_i paid amount_i to person to_i. Return the minimum number of new transactions required to settle all debts. You may create settlement transactions between any two people; the only requirement is that every person's final net balance becomes zero. Example 1 Input: transactions = [[0,1,10],[2,0,5]] Output: 2 Explanation: The final balances are: person 0 should receive 5, person 1 should pay 10, and person 2 should receive 5. One valid settlement is 1 -> 0 for 5 and 1 -> 2 for 5, requiring 2 transactions. Example 2 Input: transactions = [[0,1,10],[1,0,1],[1,2,5],[2,0,5]] Output: 1 Explanation: A single payment of 4 from person 1 to person 0 settles every balance. Constraints 1 <= transactions.length <= 8 transactions[i].length == 3 0 <= from_i, to_i <= 20 from_i != to_i 1 <= amount_i <= 100 The input is valid and all balances can be settled. Example Input [[0,1,10],[2,0,5]] Output 2