Discuss the requirements to understand what they want. Agree on an interface (eg method signature). Use TDD to work through the build so you can easily adapt to their changing requirements. Don't worry about integration or system thinking; it's more like Leetcode than the real world. Use appropriate data structures in your implementation (nothing too complicated, but don't do it a bad way). Task is basically to take some data, remap it, and pick the "top" result. Leetcode easy difficulty.