2001 U.S. Championship Puzzles

1. Number Boxes

Place the digits 1 through 9 (each used exactly once) into the circles so that the numbers inside every rectangle have the same sum.

2. Domino Stacking

You are given a set of 10 dominoes (0-1, 0-2, 0-3, 0-4, 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4). Place these dominoes into the diagram below so that each digit is different from the horizontally adjacent digits (if any) and each digit is larger than the one below it (if any).

3. Retrograde Battleship

Locate the position of the 10 ship fleet in the grid. There is one 4-unit batleship, two 3-unit cruisers, three 2-unit destroyers, and four 1-unit submarines. They do not touch each other, even diagonally. The possible placements of the ships are given. Which ones are the real ships?

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