// Starting code for Checkpoints 2 and 3 of Lab 6. This includes
// functions to read the grid and to output it.
#include
#include
#include
#include
using namespace std;
// A simple class to represent a point location. It only has a
// constructor and a two public member variables. This is one of the
// few times that you are allowed to use non-private member variables.
class Point {
public:
Point(int x0, int y0) : x(x0), y(y0) {}
int x,y;
};
// Input the grid and the start location. The input is a sequence of
// x y locations, terminated by x==0 and y==0. The last input, which
// follows 0 0 input, is the start location.
//
// The grid is represented as a 2d vector of bools, with each location
// that is blocked --- meaning that no path can go through --- being
// represented by the value "true". The grid is large enough to
// include all blocked points and include the starting location. The
// first coordinate of the vector of vectors is the x coordinate, and
// the second is the y coordinate. The format of the input is
// specified in the lab handout.
void read_grid(istream& istr, vector > & blocked_grid,
int & start_x, int & start_y) {
// Read the x y locations into a list of Points. Keep track of the
// max x and max y values so that the size of the grid can be
// determined.
int x, y;
int max_x = 0, max_y = 0; // keep track of the max coordinate values
list blocked_points;
while ((istr >> x >> y) && ! (x==0 && y==0)) {
blocked_points.push_back(Point(x,y));
if (x > max_x) max_x = x;
if (y > max_y) max_y = y;
}
// Now that a 0 0 location has been read, read the start location.
// If this is beyond the max x or y value then update these values.
istr >> start_x >> start_y;
if (start_x > max_x) max_x = start_x;
if (start_y > max_y) max_y = start_y;
// Make a vector of vectors with all entries marked false.
vector one_row_of_ys(max_y+1, false);
vector > empty_grid(max_x+1, one_row_of_ys);
blocked_grid = empty_grid;
// For Point in the list, mark the location in the list as blocked.
list::iterator p;
for (p = blocked_points.begin(); p != blocked_points.end(); ++p) {
blocked_grid[p->x][p->y] = true;
}
}
// Output the grid to cout. The form of the output is explained in
// the cout statement below.
void print_grid(vector > const& blocked_grid, int start_x, int start_y) {
cout << "Here is the grid with the origin in the upper left corner, x increasing \n"
<< "horizontally and y increasing down the screen. An 'X' represents a blocked\n"
<< "location and the 'S' represents the starting location.\n\n";
for (int y=0; y > blocked_grid;
int start_x, start_y;
read_grid(istr, blocked_grid, start_x, start_y);
print_grid(blocked_grid, start_x, start_y);
// Start here with your code...
return 0;
}