los.c

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#define DIM_X 60
#define DIM_Y 60

#include <stdio.h>
#include "los.h"

#define LEGUP 1

//x0 and x0 are the coordinates of the pixel under consideration, which will move towards the person
//x1 and y1 are the coordinates of the location of the person
int line () {

        const int x1 = DIM_X/2;
        const int y1 = DIM_Y/2;
        int visible = 0;
#pragma omp parallel for reduction(+:visible)
        for (int y_pixel=0; y_pixel<DIM_Y; y_pixel++) {
                for (int x_pixel=0; x_pixel<DIM_X; x_pixel++) {

                        int sight=1;
                        int x0 = x_pixel;
                        int y0 = y_pixel;
                        int sx, sy, err, dx, dy, e2;
                        if (x0 < x1) {
                                sx=1;
                                dx=x1-x0;
                        }
                        else {
                                sx=-1;
                                dx=x0-x1;
                        }

                        if (y0 < y1) {
                                sy=1;
                                dy=y1-y0;
                        }
                        else {
                                sy=-1;
                                dy=y0-y1;
                        }
                        err=dx-dy;

                        while (1) {
                                if ((x0==x1) && (y0==y1)) {
                                        break;
                                }
                                //if there's an obstacle
                                if (obstacles[y0][x0] == 1) {
                                        sight=0;
                                        break;
                                }
                                e2=2*err;
                                if (e2 > -dy) {
                                        err = err - dy;
                                        x0 = x0+sx;
                                }
                
                                if (e2 < dx) {
                                        err = err + dx;
                                        y0 = y0 + sy;
                                }
                        }       
        
                        //if an obstacle was not found on the way
                        if (sight == 1) {
                                //store 1 on the output
                                output[y_pixel][x_pixel] = 1;
                visible++;
                        }
                }
        }

    return visible;
}

int main() {
        int sum = line();
        int res = 0;
        printf ("Sum: %d\n", sum);
        if (sum == 2193) {
                printf("RESULT: PASS\n");
        } else {
                printf("RESULT: FAIL\n");
                res = 1;
        }

        return res;
}