public void Update(MaximumSumQueryObject updatedLeftChild, MaximumSumQueryObject updatedRightChild)
{
Sum = GetCombinedSum(updatedLeftChild, updatedRightChild);
MaximumSum = GetCombinedMaximumSum(updatedLeftChild, updatedRightChild);
MaximumLeftStartingSum = GetCombinedMaximumLeftStartingSum(updatedLeftChild, updatedRightChild);
MaximumRightStartingSum = GetCombinedMaximumRightStartingSum(updatedLeftChild, updatedRightChild);
}
} // [ ... <-]
public MaximumSumQueryObject Combine(MaximumSumQueryObject rightAdjacentObject)
=> new MaximumSumQueryObject
{
SegmentStartIndex = SegmentStartIndex,
SegmentEndIndex = rightAdjacentObject.SegmentEndIndex,
Sum = GetCombinedSum(this, rightAdjacentObject),
MaximumSum = GetCombinedMaximumSum(this, rightAdjacentObject),
MaximumLeftStartingSum = GetCombinedMaximumLeftStartingSum(this, rightAdjacentObject),
MaximumRightStartingSum = GetCombinedMaximumRightStartingSum(this, rightAdjacentObject)
};
private void Build(int treeArrayIndex, int segmentStartIndex, int segmentEndIndex)
{
if (segmentStartIndex == segmentEndIndex)
{
_treeArray[treeArrayIndex] = new MaximumSumQueryObject(segmentStartIndex, _sourceArray[segmentStartIndex]);
return;
}
int leftChildTreeArrayIndex = 2 * treeArrayIndex + 1;
int rightChildTreeArrayIndex = leftChildTreeArrayIndex + 1;
Build(leftChildTreeArrayIndex, segmentStartIndex, (segmentStartIndex + segmentEndIndex) / 2);
Build(rightChildTreeArrayIndex, (segmentStartIndex + segmentEndIndex) / 2 + 1, segmentEndIndex);
_treeArray[treeArrayIndex] = _treeArray[leftChildTreeArrayIndex].Combine(_treeArray[rightChildTreeArrayIndex]);
}
private void Build(int treeArrayIndex, int segmentStartIndex, int segmentEndIndex)
{
if (segmentStartIndex == segmentEndIndex)
{
_treeArray[treeArrayIndex] = new MaximumSumQueryObject(_sourceArray[segmentStartIndex]);
return;
}
int leftChildTreeArrayIndex = 2 * treeArrayIndex + 1;
int rightChildTreeArrayIndex = leftChildTreeArrayIndex + 1;
int leftChildSegmentEndIndex = (segmentStartIndex + segmentEndIndex) / 2;
Build(leftChildTreeArrayIndex, segmentStartIndex, leftChildSegmentEndIndex);
Build(rightChildTreeArrayIndex, leftChildSegmentEndIndex + 1, segmentEndIndex);
_treeArray[treeArrayIndex] = _treeArray[leftChildTreeArrayIndex].Combine(_treeArray[rightChildTreeArrayIndex]);
}
public MaximumSumQueryObject Combine(MaximumSumQueryObject rightAdjacentValue)
=> new MaximumSumQueryObject
{
// The sum is just the sum of both.
Sum = Sum + rightAdjacentValue.Sum,
// The maximum sum either intersects both segments, or is entirely in one.
MaximumSum = Math.Max(
MaximumRightStartingSum + rightAdjacentValue.MaximumLeftStartingSum,
Math.Max(MaximumSum, rightAdjacentValue.MaximumSum)),
// The maximum left starting sum starts at the left, and may or may not cross into the right.
MaximumLeftStartingSum = Math.Max(
Sum + rightAdjacentValue.MaximumLeftStartingSum,
MaximumLeftStartingSum),
// The maximum right starting sum starts at the right, and may or may not cross into the left.
MaximumRightStartingSum = Math.Max(
rightAdjacentValue.Sum + MaximumRightStartingSum,
rightAdjacentValue.MaximumRightStartingSum)
};
private static int GetCombinedMaximumRightStartingSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject)
// The maximum right starting sum starts at the right, and may or may not cross into the left.
=> Math.Max(
rightAdjacentObject.Sum + leftAdjacentObject.MaximumRightStartingSum,
rightAdjacentObject.MaximumRightStartingSum);
private static int GetCombinedMaximumSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject)
// The maximum sum either intersects both segments, or is entirely in one.
=> Math.Max(
leftAdjacentObject.MaximumRightStartingSum + rightAdjacentObject.MaximumLeftStartingSum,
Math.Max(leftAdjacentObject.MaximumSum, rightAdjacentObject.MaximumSum));
private static int GetCombinedSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject) // The sum is just the sum of both. => leftAdjacentObject.Sum + rightAdjacentObject.Sum;
private static int GetCombinedMaximumRightStartingSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject)
// The maximum right starting sum starts at the right, and may or may not cross into the left.
=> Math.Max(
rightAdjacentObject.Sum + leftAdjacentObject.MaximumRightStartingSum,
rightAdjacentObject.MaximumRightStartingSum);
private static int GetCombinedMaximumSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject)
// The maximum sum either intersects both segments, or is entirely in one.
=> Math.Max(
leftAdjacentObject.MaximumRightStartingSum + rightAdjacentObject.MaximumLeftStartingSum,
Math.Max(leftAdjacentObject.MaximumSum, rightAdjacentObject.MaximumSum));
private static int GetCombinedSum(MaximumSumQueryObject leftAdjacentObject, MaximumSumQueryObject rightAdjacentObject)
// The sum is just the sum of both.
=> leftAdjacentObject.Sum + rightAdjacentObject.Sum;
public void Update(MaximumSumQueryObject updatedLeftChild, MaximumSumQueryObject updatedRightChild)
{
Sum = GetCombinedSum(updatedLeftChild, updatedRightChild);
MaximumSum = GetCombinedMaximumSum(updatedLeftChild, updatedRightChild);
MaximumLeftStartingSum = GetCombinedMaximumLeftStartingSum(updatedLeftChild, updatedRightChild);
MaximumRightStartingSum = GetCombinedMaximumRightStartingSum(updatedLeftChild, updatedRightChild);
}
private int MaximumRightStartingSum { get; set; } // [ ... <-]
public MaximumSumQueryObject Combine(MaximumSumQueryObject rightAdjacentObject)
=> new MaximumSumQueryObject()
{
SegmentStartIndex = SegmentStartIndex,
SegmentEndIndex = rightAdjacentObject.SegmentEndIndex,
Sum = GetCombinedSum(this, rightAdjacentObject),
MaximumSum = GetCombinedMaximumSum(this, rightAdjacentObject),
MaximumLeftStartingSum = GetCombinedMaximumLeftStartingSum(this, rightAdjacentObject),
MaximumRightStartingSum = GetCombinedMaximumRightStartingSum(this, rightAdjacentObject)
};
