public static int MinimumNumberOfBoats_UdemySolution(int[] weights, int maxWeight, int weightDiff)
{
// * the solution provided by the instructor doesn't take edge cases into account. Had to add them by had.
// * algo on the last if, i had to add a comparison, since the top.key && i might be the same, and if !isTaken[i]
// * that value is never popped
// * this solution seems overly complicated, since every solution works for every other lower solution
int n = weights.Length;
if (n == 0)
{
return(0);
}
if (n == 1)
{
if (weights[0] <= weightDiff)
{
return(1);
}
return(0);
}
Array.Sort(weights);
int ans = 0;
int p = 0;
List <bool> isTaken = new List <bool>(new bool[n]);
MaxHeap <BoatKey> pq = new MaxHeap <BoatKey>();
for (int i = n - 1; i >= 0; i--)
{
while (p < i && weights[p] + weights[i] <= maxWeight)
{
pq.Insert(new BoatKey(p, weights[p]));
p++;
}
if (isTaken[i])
{
continue;
}
while (!pq.IsEmpty() && weights[i] - pq.Top().Weight <= weightDiff)
{
if (isTaken[pq.Top().Key] || i == pq.Top().Key)
{
pq.RemoveTop();
continue;
}
isTaken[i] = isTaken[pq.Top().Key] = true;
pq.RemoveTop();
break;
}
ans++;
}
return(ans);
}
public static int MonsterKiller(int[] dmg, int hp, int potions)
{
if (dmg.Length == 0)
{
return(0);
}
MaxHeap <int> kills = new MaxHeap <int>();
int i = 0;
int l = dmg.Length;
while (hp > 0 && i < l)
{
if (dmg[i] > hp)
{
if (potions == 0)
{
return(i);
}
else
{
potions--;
if (!kills.IsEmpty())
{
if (dmg[i] <= kills.Top())
{
hp += kills.RemoveTop();
kills.Insert(dmg[i]);
}
}
}
}
else
{
hp -= dmg[i];
if (dmg[i] > 0)
{
kills.Insert(dmg[i]);
}
}
i++;
}
return(i);
}