public static void RandomShuffle <T>(
this ArrayIterator <T> first,
ArrayIterator <T> last,
Func <int, int> gen
)
{
var n = Distance(first, last);
for (var i = n - 1; i > 0; --i)
{
first.GetAdvanced(i).Swap(first.GetAdvanced(gen(i + 1)));
}
}
public static ArrayIterator <T> SearchN <T>(
this ArrayIterator <T> first,
ArrayIterator <T> last,
int count,
T val,
Func <T, T, bool> pred
)
{
var limit = first.GetAdvanced(first.Distance(last) - count);
while (first.NotEqual(limit))
{
var it = first;
var i = 0;
while (pred(val, it.GetCurrent()))
{
it = it.GetNext();
if (++i == count)
{
return(first);
}
}
first = first.GetNext();
}
return(last);
}
public static ArrayIterator <T> IsHeapUntil <T>(
this ArrayIterator <T> first,
ArrayIterator <T> last,
Func <T, T, bool> comp
)
{
var len = first.Distance(last);
var p = 0;
var c = 1;
var pp = first;
while (c < len)
{
var cp = first.GetAdvanced(c);
if (comp(pp.GetCurrent(), cp.GetCurrent()))
{
return(cp);
}
c++;
cp = cp.GetNext();
if (c == len)
{
return(last);
}
if (comp(pp.GetCurrent(), cp.GetCurrent()))
{
return(cp);
}
p++;
pp = pp.GetNext();
c = 2 * p + 1;
}
return(last);
}
public static void PushHeap <T>(
this ArrayIterator <T> first,
ArrayIterator <T> last,
Func <T, T, bool> comp
)
{
if (first.Distance(last) < 2)
{
return;
}
last = last.GetPrev();
var temp = last.GetCurrent();
var parent = first.GetAdvanced((first.Distance(last) - 1) / 2);
while (first.Distance(last) > 0 && comp(parent.GetCurrent(), temp))
{
last.SetCurrent(parent.GetCurrent());
last = parent;
parent = first.GetAdvanced((first.Distance(last) - 1) / 2);
}
last.SetCurrent(temp);
}
public static void InplaceMerge <T>(
this ArrayIterator <T> first,
ArrayIterator <T> middle,
ArrayIterator <T> last,
Func <T, T, bool> comp
)
{
if (first.Index >= middle.Index || middle.Index >= last.Index)
{
return;
}
if (last.Index - first.Index == 2)
{
if (comp(middle.GetCurrent(), first.GetCurrent()))
{
Swap(first, middle);
}
return;
}
ArrayIterator <T> firstCut;
ArrayIterator <T> secondCut;
if (middle.Index - first.Index > last.Index - middle.Index)
{
firstCut = first.GetAdvanced(first.Distance(middle) / 2);
secondCut = middle.LowerBound(last, firstCut.GetCurrent(), comp);
}
else
{
secondCut = middle.GetAdvanced(middle.Distance(last) / 2);
firstCut = first.UpperBound(middle, secondCut.GetCurrent(), comp);
}
Rotate(firstCut, middle, secondCut);
middle = firstCut.GetAdvanced(middle.Distance(secondCut));
InplaceMerge(first, firstCut, middle, comp);
InplaceMerge(middle, secondCut, last, comp);
}