Thx I've got ACC. I use backtracking too, and my program runs for 0.01s only. Not bad for a Pascal program, eh?

Btw, backtracking problems are fun! Please, if there are any other problems that can be solved by backtracking, tell me.

Some problems that can be solved by backtracking/exhaustion by recursion are listed below

(Of course, some of them could be solved with the help of DP) :

00140 Bandwidth

00165 Stamps

00167 Sultan's Successors, the

00193 Graph Colouring

00195 Anagrams

00216 Getting in Line

00259 Software Allocation

00291 House of Santa Claus, the

00296 Safebreaker

00301 Transportation

00399 Another Puzzling Problem (* the 500th problem that i've solved! *)

00441 Lotto

00524 Prime Ring Problem

00539 Settlers of Catan

00565 Pizza Anyone?

00574 Sum It Up

00598 Bundling Newspapers

00628 Passwords

00639 Don't Get Rooked

00656 Optimal Programs

00729 Hamming Distance Problem

00732 Anagrams by Stack

00750 8 Queens Chess Problem

10063 Knuth's Permutation

10068 Treasure Hunt, the

10098 Generating Fast, Sorted Permutations

10186 Euro Cup 2000

10344 23 out of 5

10364 Square

10400 Game Show Math

10419 Sum-up the Primes

10422 Knights in FEN

10447 Sum-up the Primes II

10496 Collecting Beepers

10501 Simplified Shisen-Sho

10503 Domino Solitaire, the

10513 Bangladesh Sequences

10582 ASCII Labyrinth

10605 Mines for Diamonds

10637 Coprimes

[Keywords] exhaustion backtracking Pascal easy recursion problems

(p.s. how i like this abandoned topic. my free area :p)