for question 2. it seems awful but; Since there are no paranthesis and "/","*" preceeds "+","-" if there is an * or / , the leftmost one should be performed before the others. First check the case if no *,/ occurs by checking all the sums n1,n2,n3,n4; -n1,n2,n3,n4 .... (there are 2^4, either negative or positive, since summation is commutative order doesnt matter) if one of them equals to 24 then we return true and we are done. Then for each n1*n2, n1*n3... make a recursive call for the 3 remaining numbers (replacing two multiplied original numbers with the result, for example n1*n2 replacing n1 and n2; so the recursive call is for n1*n2, n3, n4) there are 6 pairs like that (12 more when "/" is checked as its not commutative). Execute the same algorithm for 3 numbers and for 2 numbers, when there is only one number left, if it is not 24 return false, if it is 24 return true.
I guess the brute force approach requires 4!*4^4, this seems to narrow the search space by exploiting the precedance and commutative rule of summation and multiplication. On Oct 2, 4:00 pm, bittu <shashank7andr...@gmail.com> wrote: > If-a-person-dials-a-sequence-of-numbers-on-the-telephone-what-possible- > words-strings-can-be-formed-from-the-letters > > We are given 4 numbers say n1, n2, n3, n4. We can place them in any > order and we can use mathematical operator +, -, *, / in between them > to have final result as 24. Write an algorithm for this, it will take > 4 numbers and return false or true whether final result 24 is possible > with any combination. > > Pretend there is a robot that has to navigate a maze (N x M). The > robot can only move down or right and the maze can contain walls. > Write an algorithm to determine the number of paths the robot can > take. > > If a person dials a sequence of numbers on the telephone, what > possible words/strings can be formed from the letters associated with > those numbers? -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
