Here is a program that will compute height of points, given relative heights measured at various points as explained in
1) All measurements are input from "swap.txt" and converted to whole numbers for accuracy
2) A table of all point names is obtained from the measurement data. Thereafter, points can be known as 1,2,3,etc. rather than string values of the point name.
3) A table is prepared with all known distances between points
4) Missing values are computed.
5) Now we can ask the user for the constant point value and prepare a table of the absolute height of all points.