zombies.c

#define _GNU_SOURCE

#include <jh.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>

#define RIFLE_SPEED 975
#define PISTOL_SPEED 375

char line[4096];
FILE *in, *out;

void next(void) {
  (void)CHK_PTR(fgets(line, sizeof(line), in), "unexpected end of input", 1);
  trim_end(line, "\r\n");
  printf("INPUT: %s\n", line);
}

double distance(double x, double y) {
  return sqrt(x*x+y*y);
}

double deg_atan(double x, double y) {
  return atan(y/x)/M_PI*180;
}

double drop(double distance, double speed, double *shot_time) {
  double t = distance/speed;
  if (shot_time) *shot_time = t;
  //printf("shot time to target: %f\n", t);
  return 0.5 * 9.81 * (t*t);
}

void sendf(char *fmt, ...) {
  va_list ap;
  char *buf;
  va_start(ap, fmt);
  (void)fail_on_neg(vasprintf(&buf, fmt, ap), "vasprintf failed", 1);
  va_end(ap);

  fputs(buf, out);
  printf("OUTPUT: %s", buf);

  free(buf);
}

int main(void) {
  if (fnetopen(&in, &out, "zombies_8977dda19ee030d0ea35e97ad2439319.2014.shallweplayaga.me", "20689", JH_TCP_HINTS))
    xperror("fnetopen failed", 0);
  do next(); while (line[0] != '3');
  sendf("2\n");
  do next(); while (line[0] != '3');
  sendf("3\n");
  do next(); while (strstr(line, "Tribbletown will only let you in") == NULL);

  while (1) {
    next();
    if (strncmp(line, "-----", 5)) xperror("start marker not found", 0);
    
    next(); // "Level <n>"
    
    next();
    if (strcmp(line, "You are still, aiming carefully from your van")) xperror("I want to be still", 0);
    
    next();
    double x0, y0, pupx, pupy, time_to_death, vx=0, vy=0, shot_time;
    if (sscanf(line, "The zombie is stalking a puppy %lfm from your van and %lfm above your van", &x0, &y0) == 2) {
      next();
      if (strcmp(line, "The zombie has no legs...it's not moving.")) xperror("IT'S MOVING! SHOOT IT! I CAN'T!", 0);
    } else if (sscanf(line, "The zombie is stalking a puppy across a hillside, starting at a distance of %lfm from your van and %lfm above it. The puppy is frozen in terror %lfm from your van and %lfm above your van.", &x0, &y0, &pupx, &pupy) == 4) {
      next();
      if (sscanf(line, "You have %lf seconds before the zombie eats the puppy!", &time_to_death) != 1) xperror("want deathtime", 0);
      printf("x1=%f y1=%f x2=%f y2=%f ttd=%f\n", x0, y0, pupx, pupy, time_to_death);
      // assume 1s reaction time
      double dx = pupx-x0, dy = pupy-y0;
      double scale = 1/time_to_death;
      vx = dx * scale;
      x0 += vx;
      vy = dy * scale;
      y0 += vy;
      printf("dx=%f dy=%f scale=%f newx=%f newy=%f\n", dx, dy, scale, x0, y0);
    } else {
      xperror("matching coords failed", 0);
    }

    next();
    if (strcmp(line, "Enter your shot details:")) xperror("i want to enter details", 0);

    double shot_angle, view_angle, dist;
    if (vx==0 && vy==0) {
      dist = distance(x0, y0);
      view_angle = deg_atan(x0, y0);
      double corrected_y = y0 + drop(dist, RIFLE_SPEED, &shot_time);
      printf("corrected y: %f\n", corrected_y);
      shot_angle = deg_atan(x0, corrected_y);
    } else {
      double t=0, dt, x, y;
      for (int i=0; i<100; i++) {
        x = x0 + t * vx;
        y = y0 + t * vy;
        dist = distance(x, y);
        view_angle = deg_atan(x, y);
        y = y + drop(dist, RIFLE_SPEED, &shot_time);
        shot_angle = deg_atan(x, y);
        // shot takes shot_time to arrive, but should arrive after t
        double t_new = (t + shot_time)/2;
        dt = t_new-t;
        t = t_new;
      }
      printf("x=%f y=%f\n", x, y);
      printf("t=%f dt=%f\n", t, dt);
    }

    sendf("r, %f, %f, %f\n", shot_angle, dist, view_angle);

    next();
    if (!strcmp(line, "1 second gone by")) next();
    if (strcmp(line, "Bullseye!, you nailed it in the face") &&
        strstr(line, "You hit the zombie, but missed his eye by")==NULL) {
      printf("not a hit\n");
      while (1) next();
    }
  }
}