LDP

A group of friends went on a trip and sometimes lent each other money. Each transaction among them is represented by the tuple (X, Y, Z) which means person ‘X’ gave person ‘Y’ $Z. Given a list of ‘N’ transactions between a group of friends, return the minimum number of transactions required to settle the debt.

Example:

Alice paid for Bill's lunch for $10. Then later Chris gave Alice $5 for a taxi ride. Assuming   Alice, Bill, and Chris are person 0, 1, and 2 respectively (0, 1, 2 are the person's ID), the transaction can be represented as [[0, 1, 10], [2, 0, 5]].So here the minimum number of transactions to settle the debt is 2.

You are given ‘N’ tasks. Each task has its own duration and deadline stored in array/list 'ARR'. You have to do all the tasks. Reward earned by doing a task is ‘deadline of the task’ - ‘time when the task is done’.

You have to order the tasks in such a way that the sum of rewards is maximized and find the maximum sum of the reward.

Note :

1. The time starts from zero. 
2. Before completing one task another task can not be started. 
3. The reward for doing a task can be negative. 

Design a library management system.