public static Output TraverseMatrixFromBack(Helfer.Matrix <int> mat)
{
for (int index = mat.Length - 2; index >= 0; index--)
{
int botEl = mat.GetRow(index) == mat.RowNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(index) + 1, mat.GetCol(index)); // If LAST ROW: int.Max ELSE: take bottom element
int rightEl = mat.GetCol(index) == mat.ColNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(index), mat.GetCol(index) + 1); // If LAST COL: int.Max ELSE: take right element
mat.SetElementAtIndex(index, mat.GetElementAtIndex(index) + Math.Min(botEl, rightEl)); // Add smaller accumulated element to current
// This means it goes along the path with the smaller sum
// The smaller sum accumulates along the path
}
Helfer.Point[] trace = new Helfer.Point[mat.RowNum + mat.ColNum - 1];
for (int ind = 0, ptTrace = 0; ptTrace < trace.Length;)
{
trace[ptTrace++] = new Helfer.Point(mat.GetRow(ind), mat.GetCol(ind));
int botEl = mat.GetRow(ind) == mat.RowNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(ind) + 1, mat.GetCol(ind));
int rightEl = mat.GetCol(ind) == mat.ColNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(ind), mat.GetCol(ind) + 1);
if (botEl < rightEl)
{
ind = mat.EncodePos(mat.GetRow(ind) + 1, mat.GetCol(ind));
}
else
{
ind = mat.EncodePos(mat.GetRow(ind), mat.GetCol(ind) + 1);
}
}
return(new Output(mat.GetElementAtIndex(0), trace, mat.mat));
}
/* Encoding: posAbs = posY * T + posX where T > MaxValueOf(posX) => T == colCount
* As long as T satisfies given Criteria following is true:
* - posY = (int) posAbs / T
* - posX = posA mod T
*
* // !!! T must be bigger than MaxValOf(posX) so pos X can be Encoded as the remainder of the number !!!
*
* posAbs = posY * (colCount+1) + posX
*
*/
private static Pos BinarySearchMatrix(Helfer.Matrix <int> mat, int tar, ref int iterations)
{
int upBound = mat.Length - 1;
int lowBound = 0;
int current;
while (upBound >= lowBound)
{
iterations++;
current = (upBound + lowBound) / 2;
int element = mat.GetElementAtIndex(current);
if (element > tar)
{
upBound = current - 1;
}
else if (element < tar)
{
lowBound = current + 1;
}
else
{
return(new Pos(mat.GetCol(current) + 1, mat.GetRow(current) + 1)); //new Pos(current % mat.GetLength(0)+1, current / mat.GetLength(1)+1); //Element equals current;
}
}
return(new Pos(-1, -1));
}
private static Pos BinarySearchMatrix2(Helfer.Matrix <int> mat, int tar, ref int iterations, int current = 0)
{
if (Helfer.BinarySearch(0, mat.Length, ref current, ref iterations, (ind) => mat.GetElementAtIndex(ind).CompareTo(tar)))
{
return(new Pos(mat.GetCol(current) + 1, mat.GetRow(current) + 1));
}
else
{
return(new Pos(-1, -1));
}
}
public static int TraverseMatrixFromBack(Helfer.Matrix <int> mat)
{
for (int index = mat.Length - 2; index >= 0; index--)
{
int botEl = mat.GetRow(index) == mat.RowNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(index) + 1, mat.GetCol(index)); // If LAST ROW: int.Max ELSE: take bottom element
int rightEl = mat.GetCol(index) == mat.ColNum - 1 ? int.MaxValue : mat.GetElement(mat.GetRow(index), mat.GetCol(index) + 1); // If LAST COL: int.Max ELSE: take right element
mat.SetElementAtIndex(index, mat.GetElementAtIndex(index) + Math.Min(botEl, rightEl)); // Add smaller accumulated element to current
// This means it goes along the path with the smaller sum
// The smaller sum accumulates along the path
}
return(mat.GetElementAtIndex(0));
}
