Sorting two corresponding arrays

Question

I have this code here that has two arrays. It sorts arr[], so that the highest value will be in index 0. Now the second array arr1[] contai

Answer 1

Rather than sort the arrays, sort the indices. I.e., you have

int arr[5]={4,1,3,6,2}
string arr1[5]={"a1","b1","c1","d1","e1"};

and you make

int indices[5]={0,1,2,3,4};

now you make a sort indices comparator that looks like this (just and idea, you'll probably have to fix it a little)

class sort_indices
{
   private:
     int* mparr;
   public:
     sort_indices(int* parr) : mparr(parr) {}
     bool operator()(int i, int j) const { return mparr[i]

now you can use the stl sort

std::sort(indices, indices+5, sort_indices(arr));

when you're done, the indices array will be such that arr[indices[0]] is the first element. and likewise arr1[indices[0]] is the corresponding pair.

This is also a very useful trick when you're trying to sort a large data object, you don't need to move the data around at every swap, just the indices.