Files
aoc2025/day7.c
2025-12-08 16:02:36 -06:00

179 lines
4.0 KiB
C

#include "lib.h"
#define DBG 0
static
ch input[32768] = {
#embed "day7_input.txt"
};
static
ch test[512] = {
#embed "day7_test.txt"
};
typedef struct { ch l[64]; } line;
static_assert(sizeof(line) == 0x40);
alignas(0x40) static
struct {
line padstart[4];
num file_stride;
num stride;
num _extra[6];
union { line l; struct { ch s[16]; num n; }; } result;
line padend;
} m;
static_assert(offsetof(typeof(m),result) % 64 == 0);
static_assert(offsetof(typeof(m),padend) % 64 == 0);
alignas(4096) ch buf1[256];
alignas(4096) num buf[256];
static
num do_part1(size_t file_len, ch file[file_len]) {
m = (typeof(m)){ };
m.result.n = 0;
#if DBG
pnl();
#endif
memset(buf1, 0, sizeof(buf1));
m.file_stride = findc(file, '\n', file_len) - file;
num linecnt = (findc(file, 0, file_len) - file) / m.file_stride;
#if DBG
print("stride "); printd(m.file_stride); pnl();
print("lines "); printd(linecnt); pnl();
#endif
num s_pos = findc(file, 'S', - 1) - 1 - file;
buf1[s_pos] = '|';
num line = 2;
do {
ch *l = file + line * m.file_stride;
for (num col = 0; col < m.file_stride - 1; col++) {
ch c = l[col];
if (c == '^') {
m.result.n += buf1[col] > 0;
buf1[col-1] |= buf1[col];
buf1[col+1] |= buf1[col];
buf1[col] = 0;
}
}
#if DBG
for (num col = 0; col < m.file_stride; col++) {
if (buf1[col] == '|') print("|");
else if (l[col] == '^') print("^");
else print(" ");
}
pnl();
#endif
line+=2;
} while (line < linecnt);
return m.result.n;
}
static
num do_part2(size_t file_len, ch file[file_len]) {
m = (typeof(m)){ };
#if DBG
pnl();
#endif
memset(buf, 0, sizeof(buf));
m.file_stride = findc(file, '\n', file_len) - file;
num linecnt = (findc(file, 0, file_len) - file) / m.file_stride;
#if DBG
print("stride "); printd(m.file_stride); pnl();
print("lines "); printd(linecnt); pnl();
#endif
num s_pos = findc(file, 'S', - 1) - 1 - file;
buf[s_pos] = 1;
num line = 2;
do {
ch *l = file + line * m.file_stride;
for (num col = 0; col < m.file_stride - 1; col++) {
ch c = l[col];
if (c == '^') {
buf[col-1] += buf[col];
buf[col+1] += buf[col];
buf[col] = 0;
}
}
for (num col = 0; col < m.file_stride; col++) {
num v = buf[col];
#if DBG
if (l[col] == '^') print(" ");
else if (v >> 32) print("");
else if (v >> 16) print("");
else if (v >> 8) print("");
else if (v >> 4) print("");
else if (v >> 2) print("-");
else if (v >> 0) print(".");
else print(" ");
#endif
}
#if DBG
pnl();
#endif
line+=2;
} while (line < linecnt);
m.result.n = 0;
for (num col = 0; col < m.file_stride; col++) {
m.result.n += buf[col];
}
return m.result.n;
}
#define RUN_TEST1 1
#define RUN_PART1 1
#define RUN_TEST2 1
#define RUN_PART2 1
#define TEST1_EXPECT 21
#define TEST2_EXPECT 40
void run() {
#if RUN_TEST1
print("PART 1 TEST: ");
if (num v = do_part1(countof(test), test); v != TEST1_EXPECT) {
print("FAILED (got ");
printd(v);
print(", expected " xstr(TEST1_EXPECT) ")\n");
} else {
print("PASSED\n");
}
#endif
#if RUN_PART1
print("PART 1 RESULT: ");
printd(do_part1(countof(input), input));
print("\n");
#endif
#if RUN_TEST2
print("PART 2 TEST: ");
if (num v = do_part2(countof(test), test); v != TEST2_EXPECT) {
print("FAILED (got ");
printd(v);
print(", expected " xstr(TEST2_EXPECT) ")\n");
} else {
print("PASSED\n");
}
#endif
#if RUN_PART2
print("PART 2 RESULT: ");
printd(do_part2(countof(input), input));
print("\n");
#endif
exit_group(0);
}