Survo puzzles: www.survo.fi/puzzles --------------------------------------- Copyright (c) Survo Systems 2006-2012 The easiest way to solve these three problems may be using a Java Applet http://www.survo.fi/swap/puzzles.html based on the swapping method. Survo puzzle 264/2012 (25) #343-990 A B C D 1 * 9 * * 29 2 * * * 7 33 3 * * * * 16 8 23 31 16 Survo puzzle 265/2012 (80) #343-33460 A B C D 1 * * * * 39 2 * * * * 17 3 * * * * 22 23 9 29 17 Survo puzzle 266/2012 (150) #343-37755 A B C D 1 * * * * 22 2 * * * * 17 3 * * * * 39 10 17 21 30