Is Minimum Money Required Before Transactions easy or hard?

The problem is classified as Hard on LeetCode because the greedy insight is not immediately obvious. Many developers initially try simulation or dynamic programming before recognizing the optimal ordering strategy. Once the loss vs profit observation is clear, the implementation becomes straightforward.

Minimum Money Required Before Transactions Python/Java solution

The greedy algorithm can be implemented easily in Python, Java, C++, C#, or JavaScript. Sort transactions based on their net loss characteristics, iterate through them, and track the maximum required balance before executing each transaction. The core logic is only a few lines once the ordering rule is defined.

How to solve Minimum Money Required Before Transactions in O(n)?

A linear scan solution is possible by separating loss transactions and profitable ones. Sum the total losses from transactions where cost > cashback and track the maximum cost requirement among them. Combine that with the largest upfront requirement from profitable transactions to compute the minimum starting money. This reasoning reduces sorting overhead and works in O(n) time.

What is the best approach for Minimum Money Required Before Transactions?

The greedy strategy based on net transaction loss is the most efficient approach. Separate transactions where cost exceeds cashback and process the worst losses first while delaying profitable ones. This ensures you reserve enough money for the most expensive requirement. The typical implementation runs in O(n log n) time due to sorting.

Is Minimum Money Required Before Transactions asked at Google/Amazon/Meta?

Problems involving transaction ordering, greedy optimization, and minimum starting balance appear frequently in interviews at companies like Amazon, Google, and Meta. Variants of this problem test whether candidates can recognize greedy patterns and reason about worst-case ordering scenarios.

What data structure is used in Minimum Money Required Before Transactions?

The solution primarily uses arrays to store transactions and optionally sorting to reorder them. No complex data structures are required. The algorithm relies on greedy reasoning and simple iteration to track the maximum required balance.

What is the time complexity of Minimum Money Required Before Transactions?

The optimal greedy solution runs in O(n log n) time because transactions are sorted based on their cost and cashback relationship. After sorting, a single pass calculates the maximum required upfront money. Space complexity is O(1) apart from the input storage.

Description Hints 3 Solution Video 14:00

2412. Minimum Money Required Before Transactions

Hard42.1% acceptance1 company

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

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 >= cost_i must hold true. After performing a transaction, money becomes money - cost_i + cashback_i.

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 <= cost_i, cashback_i <= 10⁹

Asked at 1 company

Amazon

Topics

Hints open one at a time

Hint 1

Split transactions that have cashback greater or equal to cost apart from transactions that have cashback less than cost. You will always earn money in the first scenario.

Hint 2

For transactions that have cashback greater or equal to cost, sort them by cost in descending order.

Hint 3

For transactions that have cashback less than cost, sort them by cashback in ascending order.

14:00

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution

LanguageLoading editor…

1class Solution:
2    def minimumMoney(self, transactions: List[List[int]]) -> int:
3        

Starter codePython 3Spaces: 4

Examples

Case 1Case 2

Input

[[2,1],[5,0],[4,2]]

Input

[[3,0],[0,3]]

Your code is saved on this device.Solution