Greenoïd #6 - A project to sink

Mission

It's working! The countdown has moved back four hours to the execution of AURA's tragic plan. The pressure is off. It's only a truce, but you now have a little more time to get out of this nightmare. Digging through the data at your disposal, you discover a file bearing the name Project Abyssum. Your blood runs cold as you access its contents. This project of dams and extraction systems, led by the most powerful tribes in Greenoid, was supposed to revolutionise water management, but it is in fact one of the main reasons for AURA's anger! Corrupt and poorly managed, Abyssum encourages the excessive appropriation of resources by certain tribes to the detriment of others, and threatens the overall balance of your ecosystem.

We need to think fast. Could stopping this project prevent the AI from triggering the apocalypse? Hazel suggests connecting remotely to the Abyssum network to try and sabotage it. You manage to locate the various valves that control the flow of water in the underground infrastructures. You have to find the ones that are best placed to render the project inoperative. Your plan is risky: if you fail, not only could you make the situation worse, but you could also be detected by AURA. Your hands are shaking, but you have no choice.

Rules

Abyssum are valves that pump water from the natural springs of Arboria. A vast network then shares the water between the tribes and villages. But this sharing is not equitable, and too much water is being used, AURA's indicators are clear on this.

The project will have to be slowed down or stopped. To achieve this, you decide to launch targeted actions on key points in the Abyssum network. To find these key points, you have at your disposal: (we're concentrating on one part of the project)

• The flows from 3 feeder valves, which draw water directly from the springs. These valves are V1A, V1B, V1C
  • V for ‘Valve
  • 1 because they are on the first level
  • a letter to identify them
  • For each valve you have its flow rate, in L/s.

• The network sequences (in the ‘network’ variable). Each item of information is in this form:
  • V1C:V2C,V2A,V2D
  • This means that the water from valve V1C flows into valves V2C, V2A and V2D.
  • The water will therefore be divided equally between 3 valves.
  • If V1A receives 1200 L/s, then V2C, V2A and V2D each receive 400 L/s from V1A (values will be rounded down to the nearest whole number). Each ‘child’ valve receives the same quantity of water from its ‘parent’ valve.)

• The Abyssum has 4 levels of valves that flow from one another, always from the higher levels to the next, but several valves at level N can feed the same valve at level N+1.

You need to return the valve or valves on level 4 that receive the most water (highest flow rate), in the form :

‘flow‘_’code of the valve(s) concerned’ (if equal)

For example:

• 1 single valve: 826_V4G
• 2 valves: 1132_V4AV4C (no separation between the valves, in the order of their letter)