/// <summary>
/// This method assumes there is at least one positive number in the array.
/// Otherwise it will break </summary>
/// <param name="arr">
/// @return </param>
public virtual Triplet kadane(int[] arr)
{
int sum = 0;
int cStart = 0;
int mStart = 0;
int end = 0;
int maxSum = int.MinValue;
for (int i = 0; i < arr.Length; i++)
{
sum += arr[i];
if (sum <= 0)
{
sum = 0;
cStart = i + 1;
}
else
{
if (sum > maxSum)
{
maxSum = sum;
mStart = cStart;
end = i;
}
}
}
Triplet p = new Triplet();
p.sum = maxSum;
p.start = mStart;
p.end = end;
return(p);
}
public virtual Triplet findTriplet(int[] input, int sum)
{
Array.Sort(input);
for (int i = 0; i < input.Length - 2; i++)
{
int start = i + 1;
int end = input.Length - 1;
int new_sum = sum - input[i];
while (start < end)
{
if (new_sum == input[start] + input[end])
{
Triplet t = new Triplet(this);
t.a = input[i];
t.b = input[start];
t.c = input[end];
return(t);
}
if (new_sum > input[start] + input[end])
{
start++;
}
else
{
end--;
}
}
}
return(null);
}
public virtual IList <int?> mergeUsingHeap(IList <IList <int?> > chunks)
{
IList <int?> result = new List <int?>();
PriorityQueue <Triplet> queue = new PriorityQueue <Triplet>();
//add first element of every chunk into queue
for (int i = 0; i < chunks.Count; i++)
{
Triplet p = new Triplet(this);
p.pos = i;
p.val = chunks[i][0];
p.index = 1;
queue.add(p);
}
while (!queue.Empty)
{
Triplet p = queue.poll();
result.Add(p.val);
if (p.index < chunks[p.pos].Count)
{
p.val = chunks[p.pos][p.index];
p.index += 1;
queue.add(p);
}
}
return(result);
}
/// <summary>
/// If it is not guaranteed that tour exists then once you get
/// result of kadanewrap make an actual trip to see if value is positive </summary>
/// <returns> -1 if no solution exists otherwise returns gas station at which to start. </returns>
public virtual int startTour1(int[] gasAvailable, int[] gasRequired)
{
int[] diff = new int[gasAvailable.Length];
for (int i = 0; i < diff.Length; i++)
{
diff[i] = gasAvailable[i] - gasRequired[i];
}
bool allNegative = true;
for (int i = 0; i < diff.Length; i++)
{
if (diff[i] >= 0)
{
allNegative = false;
break;
}
}
if (allNegative)
{
return(-1);
}
KadaneWrapArray kwa = new KadaneWrapArray();
Triplet t = kwa.kadaneWrap(diff);
//make sure this solution leads to answer
int i1 = t.start;
int netGas = 0;
do
{
netGas += diff[i1];
i1 = (i1 + 1) % diff.Length;
if (netGas < 0)
{
return(-1);
}
} while (i1 != t.start);
return(t.start);
}
public virtual Triplet kadaneWrap(int[] arr)
{
Triplet straightKadane = kadane(arr);
int sum = 0;
for (int i = 0; i < arr.Length; i++)
{
sum += arr[i];
arr[i] = -arr[i];
}
Triplet wrappedNegKadane = kadane(arr);
for (int i = 0; i < arr.Length; i++)
{
arr[i] = -arr[i];
}
if (straightKadane.sum < sum + wrappedNegKadane.sum)
{
straightKadane.sum = wrappedNegKadane.sum + sum;
straightKadane.start = wrappedNegKadane.end + 1;
straightKadane.end = wrappedNegKadane.start - 1;
}
return(straightKadane);
}