#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdint.h>

char **get_lines_n(const char *filename, int *len) {
	FILE *f = fopen(filename, "r");
	fseek(f, 0, SEEK_END);
	long fsize = ftell(f);
	fseek(f, 0, SEEK_SET);

	char *string = malloc(fsize + 1);
	fread(string, 1, fsize, f);
	fclose(f);

	string[fsize] = 0;

	int i, blks = 0;
	char **lines = malloc(101 * sizeof(char *));
	char *line;
	char *str, *saveptr;

	for(i = 0, str = string; ; i++, str = NULL) {
		if(i >= 100) {
			i = 0;
			blks++;
			lines = realloc(lines, (100 * (1 + blks) + 1) * sizeof(char *));
		}
		char *tmp = strtok_r(str, "\n", &saveptr);
		if(tmp == NULL) {
			lines[100*blks + i] = NULL;
			break;
		}
		line = malloc(sizeof(char) * (strlen(tmp)+1));
		strcpy(line, tmp);
		lines[100*blks + i] = line;
	}

	*len = i;

	free(string);

	return lines;
}

char **get_lines(const char *filename) {
	int foo;

	return get_lines_n(filename, &foo);
}

void free_lines(char **lines) {
	int i = 0;
	char *line = lines[0];
	while(line != NULL) {
		free(line);
		line = lines[++i];
	}
	free(lines);
}

typedef struct instruction {
	int opcode;
	int arg1;
	int arg2;
} instruction;

void part23() {
	int len;
	char **lines = get_lines_n("23.txt", &len);
	char *line, *saveptr;
	int i = 0;
	instruction *instructions = malloc(sizeof(instruction) * len);

	/* "Opcodes":
		0 - hlf
		1 - tpl
		2 - inc
		3 - jmp
		4 - jie
		5 - jio
	    Arguments are registers (0: a, 1: b) or offsets
	*/

	while(lines[i] != NULL) {
		line = lines[i];
		int opcode;
		char *ins = strtok_r(line, " ", &saveptr);
		switch(ins[0]) {
			case 'h':
				opcode = 0;
				break;
			case 't':
				opcode = 1;
				break;
			case 'i':
				opcode = 2;
				break;
			case 'j':
				if(ins[1] == 'm') {
					opcode = 3;
				} else if(ins[2] == 'e') {
					opcode = 4;
				} else {
					opcode = 5;
				} break;
		}
		instructions[i].opcode = opcode;

		ins = strtok_r(NULL, ",", &saveptr);
		if(ins[0] == 'a')
			instructions[i].arg1 = 0;
		else if(ins[0] == 'b')
			instructions[i].arg1 = 1;
		else
			instructions[i].arg1 = atoi(ins);

		if(opcode == 4 || opcode == 5)
			instructions[i].arg2 = atoi(strtok_r(NULL, ",", &saveptr));
		i++;
	}

	int part2 = 0;
	int a;
again:	a = part2;
	int b = 0;
	int ip = 0;
	int r;
	while(ip >= 0 && ip < len) {
		instruction cur = instructions[ip];
		if(cur.opcode == 0) {
			if(cur.arg1)
				b /= 2;
			else
				a /= 2;
			ip++;
		} else if(cur.opcode == 1) {
			if(cur.arg1)
				b *= 3;
			else
				a *= 3;
			ip++;
		} else if(cur.opcode == 2) {
			if(cur.arg1)
				b++;
			else
				a++;
			ip++;
		} else if(cur.opcode == 3) {
			ip += cur.arg1;
		} else if(cur.opcode == 4) {
			r = (cur.arg1) ? b : a;
			if(r % 2 == 0)
				ip += cur.arg2;
			else
				ip++;
		} else {
			r = (cur.arg1) ? b : a;
			if(r == 1)
				ip += cur.arg2;
			else
				ip++;
		}
	}

	printf("%d\n", b);

	if(!part2) {
		part2 = 1;
		goto again;
	}

	free_lines(lines);
	free(instructions);

}

void reverse(int n[], int len) {
	int start = 0;
	int end = len;

	while(start < end) {
		int tmp = n[start];
		n[start] = n[end];
		n[end--] = tmp;
		start++;
	}
}

int min_count = 100;
long long min_product = INT_MAX;
int nums[30];

void recursive_search(int offset, int remaining, int count, long long product) {
	if(count > min_count)
		return;

	while(nums[offset] != 0) {
		if(nums[offset] > remaining) {
			;
		}
		else if(nums[offset] == remaining) {
			if(count < min_count) {
				min_count = count;
				min_product = product * nums[offset];
			} else if(count == min_count) {
				if(product * nums[offset] < min_product)
					min_product = product * nums[offset];
			}
		}
		else {
			recursive_search(offset + 1, remaining - nums[offset], count + 1, product * nums[offset]);
		}

		offset++;
	}
}

void part24() {
	char **lines = get_lines("24.txt");
	int i = 0;

	while(lines[i] != NULL) {
		nums[i] = atoi(lines[i]);
		free(lines[i++]);
	}

	nums[i] = 0;
	reverse(nums, i-1);
	int sum = 0;
	for(i = 0; nums[i] != 0; i++)
		sum += nums[i];
	sum /= 3;

	free(lines);

	recursive_search(1, sum - nums[0], 2, nums[0]);

	printf("%I64d\n", min_product);

	min_count = 100;
	min_product = INT_MAX;

	sum *= 3;
	sum /= 4;

	recursive_search(1, sum - nums[0], 2, nums[0]);

	printf("%I64d\n", min_product);
}

void part25() {
	char **lines = get_lines("25.txt");
	char *line = lines[0];
	int i = 0;

	while(!isdigit(line[i++]));
	int x = atoi(line + i - 1);
	while(isdigit(line[i++]));
	while(!isdigit(line[i++]));
	int y = atoi(line + i - 1);

	free(line);
	free(lines);

	int num = (x+y) * (x+y) - (x+y);
	num = num >> 1;
	num += 1-x;

	uint64_t result = 20151125;
	for(i = 1; i < num; i++) {
		result *= 252533;
		result %= 33554393;
	}
	printf("%I64d\n", result); // Change to %llu on *nix systems
}

int main() {
	part23();
	//part24();
	//part25();

	return 0;
}