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Homework Help: C++ Destruction Droid program

  1. Jan 6, 2010 #1
    1. The problem statement, all variables and given/known data
    Problem Destruction Droid


    Life was easy and happy on the third moon of Sirius 8: people lived and worked in the many peaceful
    colonies. However, the Klingon Empire decided to extend its control to this part of the galaxy: they
    landed a Destruction DroidTM
    on the surface of the moon. The Destruction DroidTM
    will go to one
    colony and destroy it completely. If we knew which colony is targeted by the Destruction DroidTM, then
    we could concentrate our forces to defend that colony. Fortunately, we have intercepted the commands
    transmitted to the Destruction DroidTM, thus it is possible to determine its destination. Your task is to
    write a program that determines the unfortunate colony where the Destruction DroidTM

    One of the nice things about this moon is that it is almost completely flat, hence everything can be
    described easily with two coordinates. East is x
    direction, North is y


    Each input file begins with a line containing four integers:

    n<=500, the number of commands,
    m<=100, the number of colonies,
    x and y, the starting coordinates of the Destruction DroidTM

    The first line is followed by n
    lines containing one command each. There are 5 different commands:

    LEFT p : turn left p degrees
    RIGHT p : turn right p degrees
    FASTER p : increase the speed with p units
    SLOWER p : decrease the speed with p units
    WAIT p : the Destruction DroidTM goes for p time units in the current direction with the current speed

    Speed is given in coordinate units per time units. It can be assumed that the commands do not increase
    the speed above 500 or below 0. After landing, the Destruction DroidTM faces North(y direction), and
    its speed is 0. The commands LEFT, RIGHT, FASTER, and SLOWER are executed in zero time: the
    Destruction DroidTM does not move during these commands.

    The last m lines of the input describe the colonies. Each lin ebegin swith a name of length at most 20,
    which does not contain any space characters. The name is followed by the two coordinates of the colony.


    You have to output the name of the colony where the Destruction DroidTM will be after executing the
    Write a newline character afterthe name ofthe colony. It canbe assumedthattheDestruction DroidTM will be at a distance of at most 10 from some colony, and there is a unique such colony. It is possible that the Destruction DroidTM goes through some other colonies while executing the commands, but we do not care about that.

    Sample Input

    5 4 0 0

    FASTER 10
    WAIT 10
    RIGHT 135
    SLOWER 5
    WAIT 28
    Aaaa 0 0
    Bbbb 100 100
    Cccc 0 100
    Dddd 100 0

    Sample Output


    2. Relevant equations

    all c++ you can get :biggrin:

    3. The attempt at a solution

    I was thinking about using functions. Is it necessary to use clases? I'm not sure how to make the program calculate the last position of the droid. I'll come up with some code, probably tommorrow.
    Last edited: Jan 6, 2010
  2. jcsd
  3. Jan 7, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Whether to use functions or classes is up to you, it depends on your preference.

    In the end, you will have coordinates for the position of the droid, which you need to compare to the coordinates of the colonies. I would use the following algorithm:
    Code (Text):

      int nearestColonyIndex = -1, theDistance = 0, smallestDistance = -1;
      for(i = 0; i <= count(colonies); i++) {
        theDistance = distance(droidCoordinates, colonies[i].coordinates);
        if(nearestColonyIndex == -1 || theDistance < smallestDistance) {
          smallestDistance = theDistance;
          nearestColonyIndex = i;
      cout << "The nearest colony is at index " << i << " and is named " << colonies[i].name << endl;

      int distance(int x1, y1, x2, y2) {
        // Calculate distance (squared) by Pythagorean theorem
        return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  4. Jan 13, 2010 #3
    I managed to do the program, now I need to know how to access a .txt file, so i can take data from it, and also modify data. Using functions and stdio library
  5. Jan 13, 2010 #4


    Staff: Mentor

    Use the functions whose prototypes are in stdio.h - fopen() for opening a file, fclose() for closing it when you are done, and either fscanf() or fread() for reading from the file. Presumably you have a textbook or at least some documentation that describes these functions and how to use them.
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