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day 2: simplify code

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- remove stack
- do not create useless links from/to START & END
- remove logs
This commit is contained in:
Bruno Raoult
2021-12-14 16:39:43 +01:00
parent 2dec566985
commit 94aeedb78b
3 changed files with 63 additions and 152 deletions
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201
2021/day12/aoc-c.c
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@@ -46,21 +46,18 @@
#define MAX_LINKS 10
#define MAX_NODES 128
#define START 0 /* start is always nodes[0] */
#define END 1 /* end is always nodes[1] */
#define START (&nodes[0]) /* start is always nodes[0] */
#define END (&nodes[1]) /* end is always nodes[1] */
typedef struct node {
char token[16]; /* node name */
int val; /* unused ? */
int passed; /* number of passages */
int multiple; /* can pass multiple times ? */
int nlinks; /* number of links */
struct list_head list; /* links list */
} node_t;
typedef struct link { /* links between nodes */
node_t *node; /* linked node */
int val; /* unused ? */
struct list_head list; /* next/prev link */
} link_t;
@@ -69,47 +66,14 @@ static int nnodes; /* ... and size */
static pool_t *links_pool; /* links memory pool */
static node_t* stack[1024]; /* moves stack */
static int nstack; /* ... and size */
static int npaths; /* number of solutions */
static void print_tokens()
{
log_f(3, "nodes = %d\n", nnodes);
for (int i = 0; i < nnodes; ++i) {
log(3, "%2d: %6s mult=%d passed=%d\n", i, nodes[i].token,
nodes[i].multiple, nodes[i].passed);
}
}
static void print_links()
{
struct link *link;
node_t *node;
log_f(3, "links = %d\n", nnodes);
for (int i = 0; i < nnodes; ++i) {
node = nodes+i;
log(3, "[%6s]", node->token);
list_for_each_entry(link, &node->list, list) {
log(3, " --> %s", link->node->token);
}
log(3, "\n");
}
}
/* find node from token value
* return @node or NULL
*/
static node_t *find_token(char *token)
{
log_f(2, "token=[%s]\n", token);
for (int i = 0; i < nnodes; ++i) {
log_i(4, "compare=[%s]\n", nodes[i].token);
if (!strcmp(nodes[i].token, token)) {
for (int i = 0; i < nnodes; ++i)
if (!strcmp(nodes[i].token, token))
return nodes+i;
}
}
return NULL;
}
@@ -125,158 +89,90 @@ static node_t *add_token_maybe(char *token)
strcpy(node->token, token);
node->multiple = isupper(*token)? 1: 0;
node->passed = 0;
node->nlinks = 0;
INIT_LIST_HEAD(&node->list);
nnodes++;
}
return node;
}
/* set all nodes with passed > pass (-1: all) "passed" value to zero
*/
static void clean_node_passed(int pass)
{
for (int i = 0; i < nnodes; ++i) {
if (pass == -1 || nodes[i].passed >= pass)
nodes[i].passed = 0;
}
}
/* create a link between two nodes
* return 1 if OK, 0 if error
*/
static int link_nodes(node_t *n1, node_t *n2)
{
struct link *link1, *link2;
struct link *link;
if (!((link1 = pool_get(links_pool)) && (link2 = pool_get(links_pool))))
return 0;
link1->node = n2;
list_add_tail(&link1->list, &n1->list);
link2->node = n1;
list_add_tail(&link2->list, &n2->list);
/* link from n1 to n2 */
if (n1 != END && n2 != START) { /* cannot link from END or to START */
if (!(link = pool_get(links_pool)))
return 0;
link->node = n2;
list_add_tail(&link->list, &n1->list);
}
/* link from n2 to n1 */
if (n1 != START && n2 != END) { /* cannot link from END or to START */
if (!(link = pool_get(links_pool)))
return 0;
link->node = n1;
list_add_tail(&link->list, &n2->list);
}
return 1;
}
/* read data and create tree.
/* read data and create graph.
*/
static int read_graph()
inline static int create_graph()
{
ssize_t len;
size_t alloc = 0;
char *buf = NULL, *token1, *token2;
node_t *node1, *node2;
char *buf;
if (!(links_pool = pool_init("links", 128, sizeof (struct link))))
return -1;
add_token_maybe("start");
add_token_maybe("end");
print_tokens();
add_token_maybe("start"); /* position 0 */
add_token_maybe("end"); /* position 1 */
while ((len = getline(&buf, &alloc, stdin)) > 0) {
token1 = strtok(buf, "-\n");
token2 = strtok(NULL, "-\n");
node1 = add_token_maybe(token1);
node2 = add_token_maybe(token2);
link_nodes(node1, node2);
//log_f(2, "token1=[%s] token2=[%s]\n", token1, token2);
node_t *n1 = add_token_maybe(strtok(buf, "-\n"));
node_t *n2 = add_token_maybe(strtok(NULL, "-\n"));
link_nodes(n1, n2);
}
free(buf);
print_tokens();
clean_node_passed(-1);
print_tokens();
print_links();
return nnodes;
}
/* push link ptr to stack
/* recursively traverse graph (DFS) from a node
* return solutions found
*/
inline static node_t *push(node_t *node)
static int dfs_run(node_t *node, int part, int svisited)
{
return ((stack[nstack++] = node));
}
/* pop link ptr from stack
*/
inline static node_t *pop()
{
return nstack? stack[--nstack]: NULL;
}
/* traverse graph from a node, return
*/
static int bfs_run(node_t *node, int part, int svisited)
{
int i, res = 0;
int res = 0;
struct link *link;
log_f(3, "node=%s npaths=%d\n", node->token, npaths);
//log_f(3, "node=%p nodes=%p start=%p end=%p end1=%p\n",
// node, nodes, nodes+START, nodes+END, &nodes[END]);
/* we found a path */
if (node == nodes+END) {
npaths++;
log(3, "solution :");
for (i = 0; i < nstack; ++i)
log(3, " -> %s", stack[i]->token);
log(3, "\n");
if (node == END)
return 1;
}
if (list_empty(&node->list))
return 0;
i = 0;
list_for_each_entry(link, &node->list, list) {
if (link->node != nodes+START) {
if (link->node->multiple || !link->node->passed || (part == 2 &&
!svisited)) {
int inc = 0;
link->node->passed++;
if (!link->node->multiple && link->node->passed == 2) {
log_i(3, "visited = 1\n");
svisited = 1;
inc = 1;
}
push(link->node);
res += bfs_run(link->node, part, svisited);
pop();
link->node->passed--;
if (inc) {
log_i(3, "visited = 0\n");
svisited = 0;
}
if (link->node->multiple || !link->node->passed || (part == 2 &&
!svisited)) {
int inc = 0;
link->node->passed++;
if (!link->node->multiple && link->node->passed == 2) {
svisited = 1;
inc = 1;
}
res += dfs_run(link->node, part, svisited);
link->node->passed--;
if (inc) {
svisited = 0;
}
}
}
return res;
}
/* run 1 full step.
* return number of flashed octopuses
*/
static int part1()
{
nodes[START].passed = 1;
push(nodes + START);
return bfs_run(nodes, 1, 0);
pop();
}
static int part2()
{
nodes[START].passed = 1;
push(nodes + START);
return bfs_run(nodes, 2, 0);
pop();
}
static int doit(int part)
{
read_graph();
return part == 1? part1(): part2();
create_graph();
return part == 1? dfs_run(nodes, 1, 0): dfs_run(nodes, 2, 0);
}
static int usage(char *prg)
@@ -306,6 +202,9 @@ int main(int ac, char **av)
if (optind < ac)
return usage(*av);
printf("%s : res=%d npaths=%d\n", *av, doit(part), npaths);
if (!(links_pool = pool_init("links", 128, sizeof (struct link))))
return -1;
printf("%s : res=%d\n", *av, doit(part));
exit (0);
}