easters

commit 41ecca91c386d6cd183887b5221d2f6323591ac6
parent 7b2a69401e1f3d6b419a75bccdd63c9b0026b4a9
Author: bsandro <email@bsandro.tech>
Date:   Sun, 18 Jan 2026 04:05:27 +0200

Friday: collecting extants

Diffstat:
A
friday.c
 | 
70
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 70 insertions(+), 0 deletions(-)
diff --git a/friday.c b/friday.c
@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include "cputime.h"
+
+#define MAP_W 42
+#define MAP_H 29
+
+typedef struct {
+    char grid[MAP_H][MAP_W];
+} Map;
+
+typedef struct {
+    int x;
+    int y;
+} Vec2;
+
+typedef struct {
+    Vec2 items[64];
+    int len;
+} ArVec2;
+
+inline bool isPlant(char c) {
+    return (c>='a'&&c<='z')||(c>='A'&&c<='Z');
+}
+
+inline int numConnections(Map *m, int x, int y) {
+    int n = 0;
+    if (m->grid[y-1][x]=='|') n++;
+    if (m->grid[y+1][x]=='|') n++;
+    if (m->grid[y][x-1]=='-') n++;
+    if (m->grid[y][x+1]=='-') n++;
+    return n;
+}
+
+int main(void) {
+    int prev = 0;
+    Map map = {0};
+    int x = 1;
+    int y = 1;
+    for (int c=getchar();c!=EOF;c=getchar()) {
+        if (c=='\n') {
+            y++;
+            x=1;
+        } else {
+            map.grid[y][x++] = c;
+        }
+        if (c=='\n'&&prev=='\n') break; // map end
+        prev = c;
+    }
+
+    ArVec2 extants = {0};
+
+    for (int y=1;y<MAP_H-1;++y) {
+        for (int x=1;x<MAP_W-1;++x) {
+            if (isPlant(map.grid[y][x])) {
+                if (numConnections(&map, x, y)==1) {
+                    extants.items[extants.len++] = (Vec2){x,y};
+                }
+            }
+        }
+    }
+
+    printf("%d extants:\n", extants.len);
+    for (int i=0;i<extants.len;++i) {
+        Vec2 e = extants.items[i];
+        printf("%c at %d,%d\n", map.grid[e.y][e.x], e.x, e.y);
+    }
+
+    return 0;
+}