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#include "aoc.h"
#include <algorithm>
#include <vector>
namespace aoc2021 {
static void get_length(const char** pp) {
const char* p = *pp;
while (*p >= 'a' && *p <= 'g') {
p++;
}
*pp = p;
}
// abcdefg
static char diff(line_view l1, line_view l2) {
char d[7] = {0};
auto add = [&d](line_view l) {
const char* p = l.line;
while (p < l.line + l.length) {
d[*p - 'a'] += 1;
p++;
}
};
add(l1);
add(l2);
for (int i = 0; i < 7; i++) {
if (d[i] == 1) {
return 'a' + i;
}
}
return 0;
}
struct digit {
static uint8_t is[];
uint8_t self = 0;
digit() { self = 0; }
digit(uint8_t i) { self = is[i]; }
void reset() { self = 0; }
void add(uint8_t x) { self |= x; }
void print() const noexcept {
const char* letters = "abcdefg";
for (uint8_t i = 0; i < 7; i++) {
if (self & (1 << i)) {
printf("%c", letters[i]);
}
}
printf("\n");
}
uint8_t value() const noexcept {
for (uint8_t i = 0; i < 10; i++) {
if (is[i] == self) {
return i;
}
}
return UINT8_MAX;
}
static uint8_t _or(digit d1, digit d2) noexcept { return d1.self | d2.self; }
static uint8_t _and(digit d1, digit d2) noexcept { return d1.self & d2.self; }
static uint8_t _xor(digit d1, digit d2) noexcept { return d1.self ^ d2.self; }
// 8:
// aaaa
// b c
// b c
// dddd
// e f
// e f
// gggg
static uint8_t get_a() { return _xor(digit(7), digit(1)); }
static uint8_t get_e() { return _xor(digit(8), digit(9)); }
static uint8_t get_d() { return _xor(digit(8), digit(0)); }
static uint8_t get_c() { return _xor(digit(8), digit(6)); }
static uint8_t get_f() { return digit(1).self ^ get_c(); }
static uint8_t get_b() { return _xor(digit(8), digit(2)) ^ get_f(); }
static uint8_t get_g() { return 0x40; }
static void bprint(uint8_t x) noexcept {
for (uint8_t i = 8; i > 0; i--) {
printf("%d", (x & (1 << (i - 1))) > 0 ? 1 : 0);
}
printf("\n");
}
static void test() {
bprint(get_a());
bprint(get_b());
bprint(get_c());
bprint(get_d());
bprint(get_e());
bprint(get_f());
bprint(get_g());
}
};
uint8_t digit::is[] = {0x77, 0x24, 0x5D, 0x6D, 0x2E, 0x6B, 0x7B, 0x25, 0x7F, 0x6F};
struct digitx {
line_view lv;
uint8_t get(uint8_t* digits) {
switch (lv.length) {
case 2:
return 1;
case 3:
return 7;
case 4:
return 4;
case 7:
return 8;
default:
digit d;
const char* p = lv.line;
while (p < lv.line + lv.length) {
d.add(digits[*p - 'a']);
p++;
}
return d.value();
}
}
};
int toint(digitx* d, uint8_t* digits) {
int x{0};
digitx* e = d + 4;
while (d < e) {
x = x * 10 + d->get(digits);
d += 1;
}
return x;
}
void get_digits(digitx* ds, uint8_t* digits) {
auto find = [](digitx* d, size_t l) -> std::vector<line_view> {
std::vector<line_view> vs;
for (int i = 0; i < 10; i++) {
if (d[i].lv.length == l) {
vs.push_back(d[i].lv);
}
}
return vs;
};
auto fc = [](line_view lv, char c) -> bool {
const char* p = lv.line;
while (p < lv.line + lv.length) {
if (*p == c) {
return true;
}
p++;
}
return false;
};
// 8:
// aaaa
// b c
// b c
// dddd
// e f
// e f
// gggg
auto lv1 = find(ds, 2)[0];
auto lv4 = find(ds, 4)[0];
auto lv7 = find(ds, 3)[0];
auto lv8 = find(ds, 7)[0];
auto lv069 = find(ds, 6);
char c7[7] = {0};
char a = diff(lv1, lv7);
digits[a - 'a'] = digit::get_a();
c7[0] = a;
char c4[4] = {0};
for (size_t i = 0; i < lv069.size(); i++) {
char c = diff(lv8, lv069[i]);
if (!fc(lv4, c)) {
digits[c - 'a'] = digit::get_e();
c7[1] = c;
} else {
if (!fc(lv1, c)) {
digits[c - 'a'] = digit::get_d();
c4[0] = c;
c7[2] = c;
} else {
digits[c - 'a'] = digit::get_c();
c4[1] = c;
c7[3] = c;
char f = *lv1.line == c ? *(lv1.line + 1) : *lv1.line;
digits[f - 'a'] = digit::get_f();
c4[2] = f;
c7[4] = f;
}
}
}
char b = diff(lv4, line_view{c4, 4});
digits[b - 'a'] = digit::get_b();
c7[5] = b;
char g = diff(lv8, line_view{c7, 7});
digits[g - 'a'] = digit::get_g();
// for (int i = 0; i < 14; i++) {
// printf("%d ", ds[i].get(digits));
// }
// printf("\n");
}
std::pair<int, int> day8(line_view file) {
int t0{0};
int t1{0};
auto is1478 = [](line_view lv) -> bool {
auto b1 = lv.length == 2;
auto b2 = lv.length == 3;
auto b3 = lv.length == 4;
auto b4 = lv.length == 7;
return b1 || b2 || b3 || b4;
};
per_line(file, [&t0, &t1, &is1478](line_view lv) {
digitx ds[14];
const char* p = lv.line;
int index{0};
while (p < lv.line + lv.length) {
const char* p1 = p;
get_length(&p);
ds[index].lv = line_view{p1, p};
if (index >= 10) {
t0 += int(is1478(ds[index].lv));
}
index++;
p = index == 10 ? p + 3 : p + 1;
}
uint8_t digits[7] = {0};
get_digits(ds, digits);
t1 += toint(ds + 10, digits);
return true;
});
return {t0, t1};
}
} // namespace aoc2021
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