day3p2

day3p2/Makefile

@@ -0,0 +1,12 @@
+CFLAGS := -Wall -Wextra -std=c17 -D_GNU_SOURCE
+
+LIBS := glib-2.0
+CFLAGS += $(shell pkg-config --cflags $(LIBS))
+LDLIBS := $(shell pkg-config --libs $(LIBS))
+
+.PHONY: all
+all: main
+
+.PHONY: clean
+clean:
+	rm -f main

day3p2/main.c

@@ -0,0 +1,97 @@
+#include <stdio.h>
+
+#include <glib.h>
+
+struct claim {
+    unsigned id;
+    unsigned x;
+    unsigned y;
+    unsigned w;
+    unsigned h;
+};
+
+struct claim *parseclaims(unsigned *len, const char *fname)
+{
+    FILE *f = fopen(fname, "r");
+    if (!f) {
+        perror(fname);
+        return NULL;
+    }
+
+    GArray *array = g_array_new(FALSE, FALSE, sizeof(struct claim));
+    *len = 0;
+
+    char *line = NULL;
+    size_t line_len = 0;
+    while (getline(&line, &line_len, f) != -1) {
+        struct claim claim = {0};
+
+        // Haha what is proper parsing
+        sscanf(line, "#%u @ %u,%u: %ux%u",
+                &claim.id,
+                &claim.x,
+                &claim.y,
+                &claim.w,
+                &claim.h
+        );
+
+        // Basic sanity check
+        if (claim.y > 1000 ||
+                claim.y + claim.h > 1000 ||
+                claim.x > 1000 ||
+                claim.x + claim.w > 1000) {
+            fprintf(stderr, "Warning: Ignoring out-of-bounds claim: "
+                    "#%u @ %u,%u: %ux%u\n",
+                    claim.id,
+                    claim.x,
+                    claim.y,
+                    claim.w,
+                    claim.h
+            );
+            continue;
+        }
+
+        g_array_append_val(array, claim);
+        (*len)++;
+    }
+
+    free(line);
+    fclose(f);
+    struct claim *res = (struct claim *)g_array_free(array, FALSE);
+    return res;
+}
+
+int main()
+{
+    unsigned claims_len;
+    struct claim *claims = parseclaims(&claims_len, "input");
+    if (!claims) return 1;
+
+    char (*tilemap)[1000] = g_malloc0(sizeof(char[1000][1000]));
+
+    for (struct claim *claim = claims;
+            claim < claims + claims_len; claim++) {
+        for (unsigned y = claim->y; y < claim->y + claim->h; y++) {
+            for (unsigned x = claim->x; x < claim->x + claim->w; x++) {
+                if (tilemap[y][x] >= 2) continue;
+                tilemap[y][x]++;
+            }
+        }
+    }
+
+    for (struct claim *claim = claims;
+            claim < claims + claims_len; claim++) {
+        gboolean overlap = FALSE;
+        for (unsigned y = claim->y; y < claim->y + claim->h && !overlap; y++) {
+            for (unsigned x = claim->x; x < claim->x + claim->w && !overlap; x++) {
+                overlap = (tilemap[y][x] >= 2);
+            }
+        }
+
+        if (!overlap) printf("%u\n", claim->id);
+    }
+
+    g_free(claims);
+    g_free(tilemap);
+    return 0;
+}