3 files changed, 123 insertions, 0 deletions
diff --git a/Advent-of-Code-2022/aoc-12/build.sh b/Advent-of-Code-2022/aoc-12/build.sh
new file mode 100755
index 0000000..30f495e
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-12/build.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -xe
+
+gcc -o main main.c -Wall -Wextra -pedantic
diff --git a/Advent-of-Code-2022/aoc-12/main.c b/Advent-of-Code-2022/aoc-12/main.c
new file mode 100644
index 0000000..1511059
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-12/main.c
@@ -0,0 +1,113 @@
+#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;
+}
diff --git a/Advent-of-Code-2022/aoc-12/sample.txt b/Advent-of-Code-2022/aoc-12/sample.txt
new file mode 100644
index 0000000..86e9cac
--- /dev/null
+++ b/Advent-of-Code-2022/aoc-12/sample.txt
@@ -0,0 +1,5 @@
+Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi