1 files changed, 114 insertions, 0 deletions
diff --git a/Advent-of-Code-2021/AOC-11/main.c b/Advent-of-Code-2021/AOC-11/main.c
new file mode 100644
index 0000000..b72ec5f
--- /dev/null
+++ b/Advent-of-Code-2021/AOC-11/main.c
@@ -0,0 +1,114 @@
+#include <stdio.h>
+#include <string.h>
+
+#if 0
+#define FILE_PATH "example.txt"
+#else
+#define FILE_PATH "input.txt"
+#endif
+
+#define WIDTH  10
+#define HEIGHT 10
+
+int board[WIDTH][HEIGHT] = {0};
+size_t flashes = 0;
+
+void parse()
+{
+    FILE *fp = fopen(FILE_PATH, "r");
+    if(!fp) {
+        fprintf(stderr,"ERROR: Could not open file: %s", FILE_PATH);
+        return;
+    }
+
+    char ch;
+    int i = 0;
+    while((ch = fgetc(fp)) != EOF)
+    {
+        if(ch == '\n') continue;
+        board[i%WIDTH][i/HEIGHT] = ch - '0';
+        i++;
+    }
+
+    fclose(fp);
+
+}
+
+int step()
+{
+    for(int i = 0; i < HEIGHT; i++)
+        for(int j = 0; j < WIDTH; j++)
+            board[j][i] += 1;
+
+    int new_board[WIDTH][HEIGHT] = {0};
+    size_t old_flashes = 0 - 1;
+    while(old_flashes != flashes)
+    {
+        old_flashes = flashes;
+        memcpy(new_board, board, sizeof(board));
+
+        for(int i = 0; i < HEIGHT; i++)
+            for(int j = 0; j < WIDTH; j++)
+                if(board[j][i] > 9)
+                {
+                    flashes++;
+                    new_board[j][i] = 0;
+
+                    for(int y = -1; y <= 1; y++)
+                        for(int x = -1; x <= 1; x++)
+                            if(i+y < 0 || i+y >= HEIGHT ||
+                               j+x < 0 || j+x >= WIDTH  ||
+                               (y == 0 && x == 0)) continue;
+                            else if(new_board[j+x][i+y] != 0)
+                            new_board[j+x][i+y]++;
+                }
+
+        memcpy(board, new_board, sizeof(board));
+    }
+
+    int empty_board[WIDTH][HEIGHT] = {0};
+    if(memcmp(board, empty_board, sizeof(board)) == 0)
+        return 1;
+
+    return 0;
+}
+
+void print_board()
+{
+    for(int i = 0; i < HEIGHT; i++)
+    {
+        for(int j = 0; j < WIDTH; j++)
+        {
+            printf("%d", board[j][i]);
+        }
+        puts("");
+    }
+}
+
+void part_1()
+{
+    parse();
+
+    for(int i = 0; i < 100; i++)
+        step();
+
+    printf("flashes: %ld\n", flashes);
+}
+
+void part_2()
+{
+    parse();
+
+    for(int i = 0; i < 1000000; i++)
+        if(step()) {
+            printf("synced at step: %d\n", i + 1);
+            return;
+        }
+}
+
+int main(void)
+{
+    part_1();
+    part_2();
+    return 0;
+}