Breaking Up a Chocolate Bar Puzzle - Solution

The Puzzle:

Breaking Up a Chocolate Bar
How many steps are required to break an m × n sized bar of chocolate into 1 × 1 pieces?

You can break an existing piece of chocolate horizontally or vertically.

You cannot break two or more pieces at once (so no cutting through stacks).

Our Solution:

You need m×n - 1 steps.

By breaking an existing piece horizontally or vertically, you merely increase the total number of pieces by one.

You already have 1 piece, so need m×n - 1 steps to get to m×n pieces.
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