Update index

Workflow runs for Update index

• Move a pasted Merge k Sorted Lists solution to problem 23

  completed successfully:
  Update index#2:Commit8e0684epushedbyelchibek5
  main

  Oct 18, 20268s
  More actions for workflow run 2

• Add a hints-first coach skill for coding agents

  completed successfully:
  Update index#1:Commit5babd8cpushedbyelchibek5
  main

  Oct 18, 20269s
  More actions for workflow run 1