>I think only search is okey.

>I think only search is okey.

ur solution is not good.

the better way is use remainder(mod)

I wanna offer my solution (I think, author had in view same method).
Arrange digits of the number in a such way:
(non-zero digits in arbitrary order)1234(all zeroes).
Then, we can permute only 1234 among them in order to receive a number, dividing by 7 (You can prove it).

Edited by author 12.04.2005 01:20

Is anybody willing to tell me why it works?

No sorting, just "cutting" one : 1,2,3,4 from input number; selecting zeros and constructing "possible answer" :)

cant we use dynamic programming.It is a O(2^numberofdigits) algorithm. Can any one tell me why the other solution works?

@Nickolas

> Is anybody willing to tell me why it works?

You can write a sample program and see, that permutations of 1234 produce all possible remainders in division by 7. So <some non-zero numbers><permutation on 1234><zeros> always fits.

Just use random_shuffle.