Question

Im using c++ and is using insertion sort

Where in the insertion sort algoithm should we put a counter to monitor number of item movements and number of item comparison. I have included my setup below

void InsertionSort::insertion_sort()
{
    int key,i,count = 0;
for(int j=1;j<10;j++)
 {
    key=Arr1[j];
    i=j-1;
    while(Arr1[i]>key && i>=0)
    {
     Arr1[i+1]=Arr1[i];
     i--;
     numberOfItemMovements++;
    }
    Arr1[i+1]=key;
}
}
}

as you can see, i cant seem to figure out where comparison counter should be put, although the item movement counter is good and work as expected. thanks

Answer 1

A way of getting this to work is using numberOfComparisons in the loop.

while(++numberOfComparisons && Arr1[i]>key && i>=0)
{
    Arr1[i+1]=Arr1[i];
    numberOfItemMovements++;
    i--;
}

1) Do you understand why ++numberOfComparisons can be used in the while loop but numberOfComparisons++ would fail?

2) You have a problem where Arr1[-1] could be evaluated. Can you figure out where this is happening and how you can change your code to fix it?