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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <limits.h>
#if 0
#define PART() part1(root)
#define TARGET_SIZE 100000
#else
#define PART() sz = INT_MAX; part2(root, total_size(root))
#define FILESYSTEM_SIZE 70000000
#define TARGET_SIZE 30000000
#endif
#if 0
#define FILENAME "sample.txt"
#else
#define FILENAME "input.txt"
#endif
#define MIN(x, y) (((x) < (y)) ? (x) : (y))
#define INDENT_INC 2
#define ENTRIES_CAP 256
typedef enum {
DIR,
FIL,
LINK,
} type;
typedef struct node node;
node *create_node(type t, char *name, size_t sz);
void insert_node(node *parent, node* child);
node *get_dir(node *parent, char *name);
void free_tree(node *n);
void print_tree(node *n, int indent);
size_t total_size(node *n);
size_t part1(node *n);
size_t part2(node *n, size_t total);
node *root;
node *cur;
size_t sz = 0;
void parse()
{
FILE *fp = fopen(FILENAME, "r");
if(!fp) {
fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
exit(1);
}
char line[256];
while(fgets(line, sizeof(line), fp))
{
size_t len = strlen(line);
if(line[len-1] == '\n') line[len-1] = '\0';
char *tok0 = strtok(line, " ");
char *tok1 = strtok(NULL, " ");
char *tok2 = strtok(NULL, " ");
if(tok0[0] == '$')
{
if(strcmp(tok1, "cd") != 0) continue;
if(tok2[0] == '/') cur = root;
else cur = get_dir(cur, tok2);
continue;
}
if(strcmp(tok0, "dir") == 0)
insert_node(cur, create_node(DIR, tok1, 0));
else
insert_node(cur, create_node(FIL, tok1, atoi(tok0)));
}
fclose(fp);
}
int main(void)
{
root = create_node(DIR, "/", 0);
parse();
PART();
print_tree(root, 0);
printf("%ld\n", sz);
free_tree(root);
return 0;
}
/// ------- Definitions ------- ///
struct _dir {
size_t entries_sz;
struct node *entries[ENTRIES_CAP];
};
struct _file {
size_t sz;
};
struct _link {
struct node *to;
};
struct node {
type t;
char name[16];
union {
struct _dir dir;
struct _file file;
struct _link link;
};
};
node *_create_dot(node *n)
{
node* dot = create_node(LINK, ".", 0);
dot->link.to = n;
return dot;
}
node *_create_dotdot(node *p)
{
node *dotdot = create_node(LINK, "..", 0);
dotdot->link.to = p;
return dotdot;
}
node *create_node(type t, char *name, size_t sz)
{
node *n = malloc(sizeof(node));
n->t = t;
strncpy(n->name, name, 16);
switch(t) {
case DIR:
n->dir.entries_sz = 0;
break;
case FIL:
n->file.sz = sz;
break;
case LINK:
n->link.to = NULL;
break;
}
return n;
}
void insert_node(node *parent, node* child)
{
assert(parent->t == DIR);
assert(parent->dir.entries_sz < ENTRIES_CAP);
if(child->t == DIR) {
insert_node(child, _create_dot(child));
insert_node(child, _create_dotdot(parent));
}
parent->dir.entries[parent->dir.entries_sz++] = child;
}
node *get_dir(node *parent, char *name)
{
assert(parent->t == DIR);
struct _dir dir = parent->dir;
for(int i = 0; i < dir.entries_sz; i++)
{
node *e = dir.entries[i];
if(strcmp(e->name, name) == 0) {
if(e->t == DIR)
return e;
else if(e->t == LINK)
return e->link.to;
}
}
assert("No entries found" && 0);
}
void free_tree(node *n)
{
assert(n->t == DIR);
struct _dir dir = n->dir;
for(int i = 0; i < dir.entries_sz; i++)
{
node *e = dir.entries[i];
switch(e->t) {
case DIR:
free_tree(e);
break;
case FIL:
free(e);
break;
case LINK:
free(e);
break;
}
}
free(n);
}
void print_tree(node *n, int indent)
{
for(int i = 0; i < indent; i++)
printf(" ");
printf("- ");
switch(n->t) {
case DIR:
printf("%s (dir)\n", n->name);
for(int i = 0; i < n->dir.entries_sz; i++)
print_tree(n->dir.entries[i], indent + INDENT_INC);
break;
case FIL:
printf("%s (file, size=%ld)\n", n->name, n->file.sz);
break;
case LINK:
printf("%s (link)\n", n->name);
break;
}
}
size_t total_size(node *n)
{
size_t s = 0;
switch(n->t) {
case DIR:
for(int i = 0; i < n->dir.entries_sz; i++)
s += part1(n->dir.entries[i]);
break;
case FIL:
return n->file.sz;
case LINK:
return 0;
}
return s;
}
size_t part1(node *n)
{
size_t s = 0;
switch(n->t) {
case DIR:
for(int i = 0; i < n->dir.entries_sz; i++)
s += part1(n->dir.entries[i]);
break;
case FIL:
return n->file.sz;
case LINK:
return 0;
}
if(s <= TARGET_SIZE) sz += s;
return s;
}
size_t part2(node *n, size_t total)
{
size_t s = 0;
switch(n->t) {
case DIR:
for(int i = 0; i < n->dir.entries_sz; i++)
s += part2(n->dir.entries[i], total);
break;
case FIL:
return n->file.sz;
case LINK:
return 0;
}
if((FILESYSTEM_SIZE - total) + s >= TARGET_SIZE)
sz = MIN(sz, s);
return s;
}
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