So far all the algorithms we've covered simply walk through their given ranges in order, linearly, from one element to the next. Our next family of algorithms doesn't behave that way. Instead, it takes the values of the elements in the given range and shuffles them around so that the same values still appear, but in a different order. The mathematical name for this operation is a permutation.

The simplest permutative algorithm to describe is std::sort(a,b). It does what the name implies: sort the given range so that the smallest elements appear at the front and the biggest elements at the back. To figure out which elements are "smallest," std::sort(a,b) uses operator<.

If you want a different order, you could try to overload operator< to return true under different conditions--but probably what you should do...