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#include "aoc.h"
namespace aoc2016 {
typedef void (*scramble)(char cs[8], int, int);
static int index(char cs[8], char x) {
for (int i = 0; i < 8; i++) {
if (cs[i] == x) {
return i;
}
}
return 8;
}
// swap position X with position Y
static void swap(char cs[8], int x, int y) { std::swap(cs[x], cs[y]); }
// swap letter X with letter Y
static void swap_char(char cs[8], int x, int y) {
auto xi = index(cs, (char)x);
auto yi = index(cs, (char)y);
std::swap(cs[xi], cs[yi]);
}
// rotate left/right X steps
static void rotate(char cs[8], int left, int right) {
while (left-- > 0) {
char head = cs[0];
for (int i = 1; i < 8; i++) {
cs[i - 1] = cs[i];
}
cs[7] = head;
}
while (right-- > 0) {
char tail = cs[7];
for (int i = 6; i >= 0; i--) {
cs[i + 1] = cs[i];
}
cs[0] = tail;
}
}
// rotate based on position of letter X
// determine the index of letter X
// rotate the string to the right one time
// plus a number of times equal to that index
// plus one additional time if the index was at least 4
static void rotate_char(char cs[8], int x, int) {
int i = index(cs, x);
rotate(cs, 0, i >= 4 ? 2 + i : 1 + i);
}
// reverse positions X through Y
// including the letters at X and Y
static void reverse(char cs[8], int x, int y) {
while (x < y) {
std::swap(cs[x], cs[y]);
x++;
y--;
}
}
// move position X to position Y
static void move(char cs[8], int x, int y) {
char c = cs[x];
if (x > y) {
for (int i = x; i > y; i--) {
cs[i] = cs[i - 1];
}
}
if (x < y) {
for (int i = x; i < y; i++) {
cs[i] = cs[i + 1];
}
}
cs[y] = c;
}
typedef void (*parse)(const char*, int ds[2]);
static void parse_swap(const char* p, int ds[2]) {
ds[0] = *(p + 14) - '0';
ds[1] = *(p + 30) - '0';
}
static void parse_swap_char(const char* p, int ds[2]) {
ds[0] = *(p + 12);
ds[1] = *(p + 26);
}
static void parse_rotate(const char* p, int ds[2]) {
if (*(p + 7) == 'l') {
ds[0] = *(p + 12) - '0';
}
if (*(p + 7) == 'r') {
ds[1] = *(p + 13) - '0';
}
}
static void parse_rotate_char(const char* p, int ds[2]) {
ds[0] = *(p + 35);
ds[1] = 0;
}
static void parse_reverse(const char* p, int ds[2]) {
ds[0] = *(p + 18) - '0';
ds[1] = *(p + 28) - '0';
}
static void parse_move(const char* p, int ds[2]) {
ds[0] = *(p + 14) - '0';
ds[1] = *(p + 28) - '0';
}
static void print(char* cs) {
for (int i = 0; i < 8; i++) {
auto c = cs[i];
printf("%c", c);
}
printf("\n");
}
std::pair<int64_t, int64_t> day21(line_view file) {
struct {
parse pf;
scramble sf;
} fs[] = {{parse_swap, swap}, {parse_swap_char, swap_char},
{parse_rotate, rotate}, {parse_rotate_char, rotate_char},
{parse_reverse, reverse}, {parse_move, move}};
char cs[8] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'};
per_line(
file,
[fs](line_view lv, char cs[8]) {
const char* p = lv.line;
int ds[2] = {0, 0};
int i = 6;
if (*p == 's' && *(p + 5) == 'p') {
i = 0;
}
if (*p == 's' && *(p + 5) == 'l') {
i = 1;
}
if (*p == 'r' && *(p + 1) == 'o' && *(p + 7) == 'r') {
i = 2;
}
if (*p == 'r' && *(p + 1) == 'o' && *(p + 7) == 'l') {
i = 2;
}
if (*p == 'r' && *(p + 1) == 'o' && *(p + 7) == 'b') {
i = 3;
}
if (*p == 'r' && *(p + 1) == 'e') {
i = 4;
}
if (*p == 'm') {
i = 5;
}
fs[i].pf(p, ds);
fs[i].sf(cs, ds[0], ds[1]);
print(cs);
return true;
},
cs);
print(cs);
return {0, 0};
}
} // namespace aoc2016
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