Problem
COM-B1-M06-P007 Tokens in Boxes
#7
★★☆☆☆ Level 2 of 5
Three boxes contain \(1\), \(4\), and \(9\) tokens. In one move, one token may be moved from one box to another. Can we obtain \(2\), \(6\), and \(7\)?
Check the total.
Initially there are \(14\) tokens, while the target has \(15\). Moving a token preserves the total, so the target is impossible.
Not every problem needs a complicated invariant.