Today’s tech challenge comes from Garry Trinder’s The Old New Thing.
Consider a two-dimensional board, tall and narrow. Into the board are nailed a number of horizontal obstacles. Place a water faucet at the top of the board and turn it on. The water will dribble down, and when it hits an obstacle, some of the water will go left and some will go right. The goal is to find the shortest path to the ground from a given starting position, counting both horizontal and vertical distance traveled.