#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>


int
main(int argc, char ** argv)
{
	int part = 1, cyclelimit = 220;
	int cycle;
	char buf[BUFSIZ];
	char * op, * arg;
	int opcycles = 0;
	int rx = 1, nextread = 20, interval = 40, total = 0;

	while ((cycle = getopt(argc, argv, "p:")) != -1) {
		switch (cycle) {
		case 'p':
			part = atoi(optarg);
			switch (part) {
			case 1: cyclelimit = 220; break;
			case 2: cyclelimit = 1000; break;
			default:
				fprintf(stderr, "Unexpected part: %d\n", part);
				return -1;
			}
			break;

		default:
			return -1;
		}
	}

	for (cycle = 1; cycle <= cyclelimit; ++cycle) {
		// Start of cycle. Do we need to read a new instruction?
		if (opcycles == 0) {
			char * toksave = NULL;

			if (!fgets(buf, sizeof(buf), stdin))
				break;

			op = strtok_r(buf, " \n", &toksave);
			arg = strtok_r(NULL, "\n", &toksave);

			// Just read instruction. Set op cycle count, and
			// perform any immediate actions
			if (strcmp(op, "noop") == 0 && !arg) {
				opcycles = 1;
			}
			else if (strcmp(op, "addx") == 0 && arg) {
				opcycles = 2;
			}
			else {
				fprintf(stderr, "Unexpected op/arg: %s/%s\n", op, arg ? arg : "(null)");
				return -1;
			}
		}

		// Mid-cycle debugger attachment.
		if (part == 1 && cycle >= nextread) {
			total += rx * cycle;
			nextread += interval;
		}

		// Mid-cycle CRT output.
		if (part == 2) {
			int pixel = (cycle - 1) % interval;
			int insprite = pixel >= rx - 1 && pixel <= rx + 1;
			fputc(insprite ? '#' : '.', stdout);
			if (pixel == interval - 1)
				fputc('\n', stdout);
		}

		// Perform cycle. Reduce opcycle count, do actions that occur on
		// op completion and increment cycle counter.
		--opcycles;

		if (opcycles == 0) {
			if (strcmp(op, "addx") == 0) {
				rx += atoi(arg);
			}
		}
	}

	if (part == 1)
		printf("Sum of interesting signal strengths: %d\n", total);

	return 0;
}