Day20 Day21 C WIP

2023-12-24 13:01:39 +01:00
parent 1c22f73a2b
commit 1f855400aa
9 changed files with 516 additions and 0 deletions
--- a/day21/c/day21.c
+++ b/day21/c/day21.c
@@ -0,0 +1,102 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define LINE_MAX_LENGTH 256
+
+typedef enum tile_type {
+    GARDEN_PLOT,
+    ROCK,
+    WALKED,
+} tile_type_t;
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Please specify the step number\n"); 
+        return 1;
+    }
+    int step_number = 0;
+    sscanf(argv[1], "%i", &step_number); 
+    char *p, *buf, c;
+
+    tile_type_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
+    int x = 0, y = 0;
+
+    buf = (char *)malloc(LINE_MAX_LENGTH);
+    memset(buf, 0, LINE_MAX_LENGTH);
+    p = buf;
+
+    int start[2];
+
+    while ((c = getchar()) != EOF) {
+        *p++ = c;
+        if (c == '\n') {
+            p = buf;
+            x = 0;
+            while (*p != '\n') {
+                switch (*p) {
+                    case '.':
+                        map[x][y] = GARDEN_PLOT;
+                        break;
+                    case '#':
+                        map[x][y] = ROCK;
+                        break;
+                    case 'S':
+                        map[x][y] = GARDEN_PLOT;
+                        start[0] = x;
+                        start[1] = y;
+                        break;
+                }
+                x++;
+                p++;
+            }
+            y++;
+            memset(buf, 0, LINE_MAX_LENGTH);
+            p = buf;
+        }
+    }
+
+    tile_type_t walked_curr[LINE_MAX_LENGTH][LINE_MAX_LENGTH], walked_next[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
+    memcpy(walked_curr, map, sizeof(map));
+    walked_curr[start[0]][start[1]] = WALKED;
+
+    for (int i = 0; i < step_number; i++) {
+        memcpy(walked_next, map, sizeof(map));
+        for (int j = 0; j < y; j++) {
+            for (int k = 0; k < x; k++) {
+                if (walked_curr[k][j] == WALKED) {
+                    // UP
+                    if (j > 0 && walked_next[k][j-1] == GARDEN_PLOT) {
+                        walked_next[k][j-1] = WALKED;
+                    }
+                    // LEFT
+                    if (k > 0 && walked_next[k-1][j] == GARDEN_PLOT) {
+                        walked_next[k-1][j] = WALKED;
+                    }
+                    // DOWN
+                    if (j < y - 1 && walked_next[k][j+1] == GARDEN_PLOT) {
+                        walked_next[k][j+1] = WALKED;
+                    }
+                    // RIGHT
+                    if (k < x - 1 && walked_next[k+1][j] == GARDEN_PLOT) {
+                        walked_next[k+1][j] = WALKED;
+                    }
+                }
+            }
+        }
+        memcpy(walked_curr, walked_next, sizeof(map));
+    }
+
+    int part1 = 0;
+
+    for (int i = 0; i < y; i++) {
+        for (int j = 0; j < x; j++) {
+            if (walked_curr[j][i] == WALKED) {
+                part1++;
+            }
+        }
+    }
+
+    printf("%i\n", part1);
+    free(buf);
+}