2412. Minimum Money Required Before Transactions

Problem

You are given a 0-indexed 2D integer array transactions, 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 <= 10^5

• transactions[i].length == 2

• 0 <= costi, cashbacki <= 10^9

Solution (Java)

class Solution {
    public long minimumMoney(int[][] transactions) {
        Arrays.sort(transactions,(int a[],int b[])->(a[1]-b[1]));

        long max=0,ans=0,ab=0;
        for(int a[]:transactions){
            if(a[0]>a[1]){
                max+=a[0];
                ans=Math.max(ans,max);
                max-=a[1];
            }
            else ab=Math.max(ab,a[0]);
        }
        ans=Math.max(ans,max+ab);
        return ans;
    }
}

Explain:

nope.

Complexity:

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