// Function implementing algorithm to find median so far.
int getMedian(int e, int &m, Heap &l, Heap &r)
{
// Are heaps balanced? If yes, sig will be 0
int sig = Signum(l.GetCount(), r.GetCount());
switch(sig)
{
case 1: // There are more elements in left (max) heap
if( e < m ) // current element fits in left (max) heap
{
// Remore top element from left heap and
// insert into right heap
r.Insert(l.ExtractTop());
// current element fits in left (max) heap
l.Insert(e);
}
else
{
// current element fits in right (min) heap
r.Insert(e);
}
// Both heaps are balanced
m = Average(l.GetTop(), r.GetTop());
break;
case 0: // The left and right heaps contain same number of elements
if( e < m ) // current element fits in left (max) heap
{
l.Insert(e);
m = l.GetTop();
}
else
{
// current element fits in right (min) heap
r.Insert(e);
m = r.GetTop();
}
break;
case -1: // There are more elements in right (min) heap
if( e < m ) // current element fits in left (max) heap
{
l.Insert(e);
}
else
{
// Remove top element from right heap and
// insert into left heap
l.Insert(r.ExtractTop());
// current element fits in right (min) heap
r.Insert(e);
}
// Both heaps are balanced
m = Average(l.GetTop(), r.GetTop());
break;
}
// No need to return, m already updated
return m;
}
