/*
	Dial from 0–99, start at 50.
	You get lines like L68 or R5:
	L = move left (subtract)
	R = move right (add)
	Wrap around with modulo 100.
	After each move, check if the dial is on 0.
	The password = how many times you land on 0 during the whole sequence.
*/
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[]) {
	printf("Advent Of Code Day 1 part 2\n\n");

	// remove argc so gcc wont cry
	(void)argc;

	// base vars
	int start = 50;
	int pos = start;
	int counter = 0;

	// read the input file
	char* inpf = NULL;
	inpf = argv[1];
	if (inpf == NULL) inpf = "input.txt";

	FILE* ptr = fopen(inpf, "r");
	if(ptr == NULL) {
		printf("error: no such file %s\n", inpf);
		return 1;
	}

	// process instructions
	char line[9]; // 8 chars + eol
	while(fscanf(ptr, "%9s", line) == 1) {
		char drc = line[0];
		int num = atoi(&line[1]);
		//printf("%c %d\n", drc, num);

		if (drc == 'R') {
			for(int i = 0; i < num; i++) {
				if (pos + 1 < 100) {
					pos += 1;
				} else {
					pos += 1;
					pos -= 100;
				}
				if (pos == 0) counter++;
			}
		}

		if (drc == 'L') {
			for (int i = 0; i < num; i++) {
				if (pos - 1 >= 0) {
					pos -= 1;
				} else {
					pos -= 1;
					pos += 100;
				}
				if (pos == 0) counter++;
			}
		}
	}

	printf("\npassword is: %d\n", counter);
	return 0;
}