Grid Paths & Pascal's Triangle

Path counts can be built recursively from predecessor states, and unrestricted shortest paths correspond to choosing which step positions have each direction.

What you'll learn

  • Build a grid-path count by adding the counts at all possible predecessor points.
  • Explain why unrestricted shortest paths are counted by choosing the positions of one step direction.
  • Recognize when a boundary or obstacle invalidates a direct combination count and use recursive counting instead.

Before you start

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