# RE8 | perplexity/sonar-pro | run 2

## Prompt

Minimize total time to finish these tasks, one at a time, respecting dependencies: A (2h, no deps); B (3h, needs A); C (1h, no deps); D (2h, needs B and C). Give a valid order and the total time.

## Response

A valid order is **A → B → C → D**. The **minimum total time** is **8 hours** because the tasks must be done one at a time, so the total is simply \(2 + 3 + 1 + 2 = 8\) hours[6][8].

## Why this works
- **A** has no dependencies, so it can start first.
- **B** must wait for **A**.
- **C** has no dependencies, so it can be done after **B** in a single-worker, one-at-a-time schedule.
- **D** must wait for both **B** and **C**, so it goes last.

If you want, I can also show the **earliest-start schedule** if tasks were allowed to run in parallel.
