I solved Mister B and PR Shifts using trie ... Time complexity of my code is O(n * log(n)) where maximum n = 1000000, but it takes about 1543 ms at least to get the answer, so can anyone please tell me why? Update.. some users advised me to use array instead of pointers with dynamic memory allocation and thats what I did this is the best code I came up with so far .. no dynamic memory allocating . no pointers but my code still too slow and I don't know why http://codeforces.net/contest/819/submission/28646689