Find the largest contiguous rectangle having all 1's in matrix of size m*n ; Matrix have only 0 and 1 .

Find the sum of all the multiples of 3 or 5 below 1 billion.

Since i dont want to stop hacking , i decided to post simple problem to start off the new year , Happy hacking , give its try !!!

PS: 1 billion is big no. its equal to no. of user facebook have ;)