1 files changed, 138 insertions, 0 deletions
diff --git a/Advent-of-Code-2021/AOC-5/main.c b/Advent-of-Code-2021/AOC-5/main.c
new file mode 100644
index 0000000..ea39e06
--- /dev/null
+++ b/Advent-of-Code-2021/AOC-5/main.c
@@ -0,0 +1,138 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#define MIN(x, y) (((x) < (y)) ? (x) : (y))
+
+#if 0
+#define PART_1
+#else
+#define PART_2
+#endif
+
+#if 0
+#define FILE_PATH "example.txt"
+#define WIDTH  10
+#define HEIGHT 10
+#else
+#define FILE_PATH "input.txt"
+#define WIDTH  10000
+#define HEIGHT 10000
+#endif
+
+int board[WIDTH][HEIGHT] = {0};
+
+void draw_line(int x1, int y1, int x2, int y2)
+{
+    if(x1 == x2)
+    {
+        for(int y = MIN(y1, y2); y <= MAX(y1, y2); y++)
+            board[x1][y]++;
+
+    }
+    else if(y1 == y2)
+    {
+        for(int x = MIN(x1, x2); x <= MAX(x1, x2); x++)
+            board[x][y1]++;
+    }
+#ifdef PART_2
+    else
+    {
+        int direction_x = (x1 < x2) ? 1 : -1;
+        int direction_y = (y1 < y2) ? 1 : -1;
+
+        int y = y1;
+        int x = x1;
+        while(!((y == y2) && (x == x2)))
+        {
+            board[x][y]++;
+            x+=direction_x;
+            y+=direction_y;
+        }
+    }
+#endif
+}
+
+void parse()
+{
+    FILE *fp = fopen(FILE_PATH, "r");
+    if(!fp) {
+        fprintf(stderr, "ERROR: Could not open file: %s", FILE_PATH);
+        exit(EXIT_FAILURE);
+    }
+
+    char *vec1, *vec2;
+    char line[256];
+    while(fgets(line, sizeof(line), fp) != NULL)
+    {
+        vec1 = strtok(line, " -> ");
+        vec2 = strtok(NULL, " -> ");
+
+        int x1, y1, x2, y2;
+        x1 = atoi(strtok(vec1, ","));
+        y1 = atoi(strtok(NULL, ","));
+        x2 = atoi(strtok(vec2, ","));
+        y2 = atoi(strtok(NULL, ","));
+
+        draw_line(x1, y1, x2, y2);
+    }
+}
+
+void print_board()
+{
+    for(int i = 0; i < HEIGHT; i++)
+    {
+        for(int j = 0; j < WIDTH; j++)
+        {
+            if(board[j][i] == 0)
+                putc('.', stdout);
+            else if(board[j][i] == 1)
+                putc('#', stdout);
+            else
+                putc('@', stdout);
+        }
+        putc('\n', stdout);
+    }
+}
+
+void part_1()
+{
+    parse();
+
+    int count = 0;
+    for(int i = 0; i < HEIGHT; i++)
+        for(int j = 0; j < WIDTH; j++)
+            if(board[j][i] >= 2) count++;
+
+    printf("Count is %d\n", count);
+}
+
+void part_2()
+{
+    parse();
+
+    int count = 0;
+    for(int i = 0; i < HEIGHT; i++)
+        for(int j = 0; j < WIDTH; j++)
+            if(board[j][i] >= 2) count++;
+
+    // print_board();
+
+    printf("Count is %d\n", count);
+}
+
+int main(void)
+{
+
+#ifdef PART_1
+    part_1();
+#endif
+
+#ifdef PART_2
+    part_2();
+#endif
+
+    return 0;
+}