Thread: Sort array and save the new order of elements

It would be simpler to sort array_order, using a[array_order[...]] for the compares and pivot points. Then afterwards, you can reorder or copy a according to array_order. The copy is simple, using i to index through the array, b[i] = a[array_order[i]]; . The in place reorder involves a variation of cycle sort (vA is the array, vI is the array of sorted indices):

Code:

void reorder(vector<int>& vA, vector<size_t>& vI)  
{
size_t i, j, k;
int t;
    for(i = 0; i < vA.size(); i++){
        if(i != vI[i]){
            t = vA[i];
            k = i;
            while(i != (j = vI[k])){
            // every move places a value in it's final location
                vA[k] = vA[j];
                vI[k] = k;
                k = j;
            }
            vA[k] = t;
            vI[k] = k;
        }
    }
}

Originally Posted by rcgldr

It would be simpler to sort array_order, using a[array_order[...]] for the compares and pivot points. Then afterwards, you can reorder or copy a according to array_order. The copy is simple, using i to index through the array, b[i] = a[array_order[i]]; . The in place reorder involves a variation of cycle sort (vA is the array, vI is the array of sorted indices):

Code:

void reorder(vector<int>& vA, vector<size_t>& vI)  
{
size_t i, j, k;
int t;
    for(i = 0; i < vA.size(); i++){
        if(i != vI[i]){
            t = vA[i];
            k = i;
            while(i != (j = vI[k])){
            // every move places a value in it's final location
                vA[k] = vA[j];
                vI[k] = k;
                k = j;
            }
            vA[k] = t;
            vI[k] = k;
        }
    }
}

Yes well I removed the error by just introducing a separate function for swap:

Code:

void switch_pos(int *one, int *two) {


   int temp = *one;
    *one = *two;
    *two = temp;
}