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#include <algds/str.h>
#include <algds/vec.h>
#include <algds/hash_table.h>
#include <algds/mmhash.h>
#include <string.h>
#define PANIC do { \
fprintf(stderr, "panic at %s:%d\n", __FILE__, __LINE__); \
abort(); \
} while (0)
StringVector read_mat() {
StringVector mat;
StringVector_init(&mat);
while (1) {
char *l = fgetline(stdin);
if (!l) {
return mat;
}
if (strlen(l) == 0) {
return mat;
}
int len = strlen(l);
if (l[len - 1] == '\n') {
l[len - 1] = '\0';
}
StringVector_push_back(&mat, l);
}
return mat;
}
StringVector mat;
int height;
int width;
Int2IntHashTable split(Int2IntHashTable input, const char* line, int *count) {
Int2IntHashTable new;
Int2IntHashTable_init(&new);
Int2IntHashTableIter iter = Int2IntHashTable_begin(&input);
for (; iter != NULL; iter = Int2IntHashTable_next(&input, iter)) {
int x = iter->key;
if (line[x] == '.') {
if (Int2IntHashTable_find(&new, x) == NULL) {
Int2IntHashTable_insert(&new, x, 0xff);
}
} else if (line[x] == '^') {
*count += 1;
if (x - 1 >= 0 && Int2IntHashTable_find(&new, x-1) == NULL) {
Int2IntHashTable_insert(&new, x-1, 0xff);
}
if (x + 1 < width && Int2IntHashTable_find(&new, x+1) == NULL) {
Int2IntHashTable_insert(&new, x+1, 0xff);
}
} else {
PANIC;
}
}
Int2IntHashTable_free(&input);
return new;
}
typedef struct {
int cur;
int d;
} IntPair;
uint64_t IntPair_hash(IntPair p) {
uint64_t h = 0;
h = mmhash(&p.cur, sizeof(int), h);
h = mmhash(&p.d, sizeof(int), h);
return h;
}
uint64_t IntPair_eq(IntPair a, IntPair b) {
return a.cur == b.cur && a.d == b.d;
}
HASH_TABLE_DEF(IntPair, Long)
HASH_TABLE_IMPL(IntPair, Long)
IntPair2LongHashTable cache;
void set_trace_cache(int cur, int d, long value) {
IntPair2LongHashTable_insert(&cache, (IntPair){.cur = cur, .d = d}, value);
}
bool get_trace_cache(int cur, int d, long *value) {
Long* it = IntPair2LongHashTable_get(&cache, (IntPair){.cur = cur, .d = d});
if (it == NULL) {
return false;
}
*value = *it;
return true;
}
long trace(int cur, int d) {
long cached_value = 0;
if (get_trace_cache(cur, d, &cached_value)) {
return cached_value;
}
if (cur < 0 || cur >= width) PANIC;
if (d >= height) {
return 1;
}
const char *line = mat.buffer[d];
if (line[cur] == '.') {
long ret = trace(cur, d+1);
set_trace_cache(cur, d, ret);
return ret;
} else if (line[cur] == '^') {
long ret = trace(cur+1, d+1) + trace(cur-1, d+1);
set_trace_cache(cur, d, ret);
return ret;
}
PANIC;
}
int main() {
mat = read_mat();
height = mat.size;
width = strlen(mat.buffer[0]);
Int2IntHashTable beams;
Int2IntHashTable_init(&beams);
IntPair2LongHashTable_init(&cache);
int start = -1;
for (int i = 0; i < width; i++) {
if (mat.buffer[0][i] == 'S') {
start = i;
break;
}
}
long ret = 0;
ret = trace(start, 1);
printf("%ld\n", ret);
return 0;
}
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