Re: Sorting two arrays with one call to sort()?
John wrote:
I have two separate arrays A and B. The comparison function only
depends on elements in A (keys are in A),
but the swap() function needs to swap not only A[i],A[j], but also
B[i],B[j] ; whenever it swaps A[i],A[j].
Can this be done using internal sort() of C++?
I should hope so, since the main point of the STL is to decouple algorithms
from data structures. Something like this ought to work:
struct double_iterator {
T* const a; U* const b; size_t i;
struct ref {
T& p; U& q;
ref(T& p, U& q) : p(p), q(q) {}
};
ref operator*() { return ref(a[i], b[i]); }
// ...
};
inline void operator=(ref x, ref y) { x.p = y.p; x.q = y.q; }
inline bool operator<(ref x, ref y) { return x.p < y.p; }
// ...
std::sort(double_iterator(A,B,0), double_iterator(A,B,size));
I think this will be as efficient as a hand-coded sort if you have a decent
compiler.
-- Ben
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