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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if 1
#define FILENAME "sample.txt"
#define WIDTH 8
#define HEIGHT 5
#else
#define FILENAME "input.txt"
#endif
typedef struct node_t {
char val;
struct node_t *neighbours[4]; // up, down, left, right
} node_t;
node_t graph[WIDTH][HEIGHT];
void part1();
int char_index(char ch);
int in_range(char a, char b);
void print_graph();
void part1()
{
print_graph();
}
void gen_graph(char table[WIDTH][HEIGHT])
{
for(int i = 0; i < HEIGHT; i++)
for(int j = 0; j < WIDTH; j++) {
for(int k = 0; k < 4; k++) graph[j][i].neighbours[k] = NULL;
graph[j][i].val = table[j][i];
// up
if(i > 0)
if(in_range(table[j][i], table[j][i-1]))
graph[j][i].neighbours[0] = &(graph[j][i-1]);
// down
if(i < HEIGHT - 1) {
if(in_range(table[j][i], table[j][i+1]))
graph[j][i].neighbours[1] = &(graph[j][i+1]);
}
// left
if(j > 0) {
if(in_range(table[i][j], table[j-1][i]))
graph[j][i].neighbours[2] = &(graph[j-1][i]);
}
// right
if(j < WIDTH - 1) {
if(in_range(table[j][i], table[j+1][i]))
graph[j][i].neighbours[3] = &(graph[j+1][i]);
}
}
}
void parse()
{
FILE *fp = fopen(FILENAME, "r");
if(!fp) {
fprintf(stderr, "ERROR: Could not open file: %s\n", FILENAME);
exit(1);
}
char table[WIDTH][HEIGHT] = {0};
char line[64];
for(int i = 0; fgets(line, sizeof(line), fp) != NULL && i < HEIGHT; i++)
for(int j = 0; j < WIDTH; j++)
table[j][i] = char_index(line[j]);
gen_graph(table);
fclose(fp);
}
int main(void)
{
parse();
part1();
return 0;
}
void print_graph()
{
for(int i = 0; i < HEIGHT; i++) {
for(int j = 0; j < WIDTH; j++) {
printf("(%2d %2d) %c -> ", j, i, graph[j][i].val + '`');
for(int k = 0; k < 4; k++)
printf("%c ", (graph[j][i].neighbours[k] == NULL) ? '_' :
graph[j][i].neighbours[k]->val + '`');
printf("\n");
}
printf("\n");
}
}
int char_index(char ch)
{
if(ch == 'S') ch = '`';
else if(ch == 'E') ch = '{';
return ch - '`';
}
int in_range(char a, char b)
{
if(a == b || a == b-1 || a == b+1)
return 1;
return 0;
}
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