Both a sorted array and a binary tree can let you look up an element in log(N) time. However I would expect a sorted array to be faster in practice because of the constant factor. However inserting ...

// unbalanced_binary_tree.h #ifndef UNBALANCED_BINARY_TREE_H #define UNBALANCED_BINARY_TREE_H // uncomment this line to enable move semantics; comment it to disable it. //#define MOVE_SEMANTICS ...