Plotter dilemma

1.4 Plotter dilemma

You are given a plotter which can plot points provided to it in the form of 'x' and 'y' coordinates. The plotter hand can move horizontally or vertically only. Your program will be given a list of 'n' coordinates in the form of {(x1,y1), (x2,y2} ... (xn,yn)}. Your program must print a sorted list of all 'n' points that would represent the least cumulative distance for the plotter hand to plot all 'n' points in that sorted order. If you are feeling adventurous - modify the program to provide the same output if the plotter can also move diagonally