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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if 1
#define transfer transfer_part1
#else
#define transfer transfer_part2
#endif
#if 0
#define FILENAME "sample.txt"
#define COLUMNS 3
#else
#define FILENAME "input.txt"
#define COLUMNS 9
#endif
#define STRINT(d) atoi(strtok(NULL, d)); strtok(NULL, d);
typedef struct crate crate;
crate *create_crate(char data);
void push(crate *c, int i);
crate *add(crate *c, crate *last, int i); // pushes an element to bottom of a given stack
crate *pop(int i);
void transfer_part1(int from, int to, int n);
void transfer_part2(int from, int to, int n);
void free_crates(crate *c);
void print_crate(char *format, crate *c);
crate *top[COLUMNS+1] = {0}; // +1 for part 2
void parse()
{
FILE *fp = fopen(FILENAME, "r");
if(!fp) {
fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
exit(1);
}
char line[256] = {0};
crate *last[COLUMNS] = {0};
while(fgets(line, sizeof(line), fp) != NULL)
{
if(line[0] == '\n') break; // the table has ended
for(int i = 0; i < COLUMNS; i++) {
char ch = line[(i*4)+1];
if(ch >= 'A' && ch <= 'Z') {
last[i] = add(create_crate(ch), last[i], i);
}
}
}
while(fgets(line, sizeof(line), fp) != NULL)
{
// we need to call strtok multiple times
// to get the right token (integer)
strtok(line, " ");
int n = STRINT(" ");
int from = STRINT(" ");
int to = STRINT(" ");
transfer(from-1, to-1, n);
}
fclose(fp);
}
int main(void)
{
parse();
for(int i = 0; i < COLUMNS; i++) {
print_crate("%c", top[i]);
free_crates(top[i]);
}
puts("");
return 0;
}
struct crate {
char data;
struct crate *prev;
};
crate *create_crate(char data)
{
crate *c = malloc(sizeof(crate));
c->data = data;
c->prev = NULL;
return c;
}
void push(crate *c, int i)
{
c->prev = top[i];
top[i] = c;
}
crate *add(crate *c, crate *last, int i)
{
if(last == NULL) {
push(c, i);
return c;
}
last->prev = c;
return c;
}
crate *pop(int i)
{
if(top[i] == NULL) {
fprintf(stderr, "ERROR: Column %d is empty, can't pop\n", i);
exit(1);
}
crate *c = top[i];
top[i] = c->prev;
return c;
}
void transfer_part1(int from, int to, int n)
{
for(int i = 0; i < n; i++)
push(pop(from), to);
}
void transfer_part2(int from, int to, int n)
{
transfer_part1(from, COLUMNS, n);
transfer_part1(COLUMNS, to, n);
}
void free_crates(crate *c)
{
if(c == NULL) return;
crate *prev = c->prev;
free(c);
free_crates(prev);
}
void print_crate(char *format, crate *c)
{
if(c == NULL) return;
printf(format, c->data);
}
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