2412. Minimum Money Required Before Transactions

Description

You are given a 0-indexed 2D integer array , where transactions[i] = [costi, cashbacki].

The array describes transactions, where each transaction must be completed exactly once in some order. At any given moment, you have a certain amount of money. In order to complete transaction i, money >= costi must hold true. After performing a transaction, money becomes money - costi + cashbacki.

Return the minimum amount of money required before any transaction so that all of the transactions can be completed regardless of the order of the transactions.

 

Example 1:

Input: transactions = [[2,1],[5,0],[4,2]]
Output: 10
Explanation:
Starting with money = 10, the transactions can be performed in any order.
It can be shown that starting with money < 10 will fail to complete all transactions in some order.

Example 2:

Input: transactions = [[3,0],[0,3]]
Output: 3
Explanation:
- If transactions are in the order [[3,0],[0,3]], the minimum money required to complete the transactions is 3.
- If transactions are in the order [[0,3],[3,0]], the minimum money required to complete the transactions is 0.
Thus, starting with money = 3, the transactions can be performed in any order.

 

Constraints:

• 1 <= transactions.length <= 105
• transactions[i].length == 2
• 0 <= costi, cashbacki <= 109

 

Solutions

Solution: Greedy

• Time complexity: O(n)
• Space complexity: O(1)

 

JavaScript

/**
 * @param {number[][]} transactions
 * @return {number}
 */
const minimumMoney = function (transactions) {
  let maxCost = 0;
  let maxCashback = 0;
  let losses = 0;

  for (const transaction of transactions) {
    const [cost, cashback] = transaction;

    if (cost > cashback) {
      losses += cost - cashback;
      maxCashback = Math.max(cashback, maxCashback);
    } else {
      maxCost = Math.max(cost, maxCost);
    }
  }

  return losses + Math.max(maxCashback, maxCost);
};