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#include "aoc.h"
namespace aoc2016 {
static int registers[4] = {7, 0, 0, 0};
static int& get(int i) { return registers[i]; }
// c = a,b,c,d
static int& get(char c) { return get(c - 'a'); }
struct instruction23 {
mutable size_t toggles = 0;
line_view todo;
instruction23(line_view l) : todo(l) {}
int which() {
// std::cout << todo << std::endl;
const char* p = todo.line;
bool toggle_is_odd = toggles & 1;
switch (*p) {
case 'c':
return toggle_is_odd ? 3 : 0;
case 'i':
return toggle_is_odd ? 2 : 1;
case 'd':
return toggle_is_odd ? 1 : 2;
case 'j':
return toggle_is_odd ? 0 : 3;
case 't':
return toggle_is_odd ? 1 : 4;
default:
break;
}
return 5;
}
};
static void get_number(const char** pp, int* d) {
const char* p = *pp;
int sign = 1;
if (*p == '-') {
sign = -1;
p += 1;
}
while (*p >= '0' && *p <= '9') {
*d = *d * 10 + *p - '0';
p++;
}
*d *= sign;
*pp = p;
}
typedef void (*todo_f)(size_t*, const char*, const std::vector<instruction23>&);
static void cpy(size_t* i, const char* p, const std::vector<instruction23>& todos) {
int d{0};
if (*p >= 'a' && *p <= 'd') {
d = get(*p);
p += 2;
} else {
get_number(&p, &d);
p += 1;
}
if (*p >= 'a' && *p <= 'd') {
get(*p) = d;
}
*i += 1;
}
static void inc(size_t* i, const char* p, const std::vector<instruction23>& todos) {
get(*p) += 1;
*i += 1;
}
static void dec(size_t* i, const char* p, const std::vector<instruction23>& todos) {
get(*p) -= 1;
*i += 1;
}
static void jnz(size_t* i, const char* p, const std::vector<instruction23>& todos) {
int d{0};
bool condition = false;
bool is_number = false;
if (*p >= '0' && *p <= '9') {
is_number = true;
get_number(&p, &d);
condition = d != 0;
} else {
condition = get(*p) != 0;
}
if (condition) {
p += is_number ? 1 : 2;
int offset{0};
if (*p >= 'a' && *p <= 'd') {
offset = get(*p);
} else {
get_number(&p, &offset);
}
*i += offset;
} else {
*i += 1;
}
}
static void tgl(size_t* i, const char* p, const std::vector<instruction23>& todos) {
size_t next = *i + get(*p);
if (next < todos.size()) {
todos[next].toggles += 1;
}
*i += 1;
}
static void non(size_t* i, const char* p, const std::vector<instruction23>&) { *i += 1; }
static size_t exec(size_t i, const std::vector<instruction23>& todos) {
todo_f fs[6] = {cpy, inc, dec, jnz, tgl, non};
// const char *ds[6] = {"cpy", "inc", "dec", "jnz", "tgl", "non"};
auto d = todos[i];
auto x = d.which();
// char param[30] = {0};
// memcpy(param, d.todo.line + 4, d.todo.length - 4);
// printf("%s %s\n", ds[x], param);
fs[x](&i, d.todo.line + 4, todos);
// printf("%d %d %d %d\n", get('a'), get('b'), get('c'), get('d'));
return i;
}
std::pair<int64_t, int64_t> day23(line_view file) {
std::vector<instruction23> todos;
per_line(file, [&todos](line_view lv) {
todos.emplace_back(line_view{lv.line, lv.length - 1});
return true;
});
size_t i = 0;
while (i < todos.size()) {
i = exec(i, todos);
}
return {get('a'), 0};
}
} // namespace aoc2016
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