1 files changed, 65 insertions, 0 deletions
diff --git a/day6.c b/day6.c
new file mode 100644
index 0000000..02d75e5
--- /dev/null
+++ b/day6.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main() {
+  int i, j,
+      rs, cs, re, ce,
+      numlights = 0, brightness = 0;
+  int** lights; int** lights2;
+  char istr[10];
+
+  lights = (int**) malloc(1000*sizeof(int*));
+  lights2 = (int**) malloc(1000*sizeof(int*));
+  for(i = 0; i < 1000; i++) {
+    lights[i] = (int*) malloc(1000*sizeof(int));
+    memset(lights[i], 0, 1000);
+    lights2[i] = (int*) malloc(1000*sizeof(int));
+    memset(lights2[i], 0, 1000);
+  }
+
+  while(scanf("%s", istr) != EOF) {
+    if(strncmp(istr, "turn", 4) == 0)
+      scanf("%s %d,%d through %d,%d", istr, &rs, &cs, &re, &ce);
+    else
+      scanf("%d,%d through %d,%d", &rs, &cs, &re, &ce);
+
+    if(strncmp(istr, "on", 2) == 0) {
+      for(i = rs; i <= re; i++)
+        for(j = cs; j <= ce; j++) {
+          lights[i][j] = 1;
+          lights2[i][j] += 1;
+        }
+    } else if(strncmp(istr, "off", 3) == 0) {
+      for(i = rs; i <= re; i++)
+        for(j = cs; j <= ce; j++) {
+          lights[i][j] = 0;
+          if(lights2[i][j]) lights2[i][j] -= 1;
+        }
+    } else if(strncmp(istr, "toggle", 6) == 0) {
+      for(i = rs; i <= re; i++)
+        for(j = cs; j <= ce; j++) {
+          lights[i][j] = !lights[i][j];
+          lights2[i][j] += 2;
+        }
+    }
+  }
+
+  for(i = 0; i < 1000; i++)
+    for(j = 0; j < 1000; j++) {
+      if(lights[i][j]) numlights++;
+      brightness += lights2[i][j];
+    }
+
+  printf("Number of lights that are on: %d\n", numlights);
+  printf("Total brightness: %d\n", brightness);
+
+  for(i = 0; i < 1000; i++) {
+    free(lights[i]);
+    free(lights2[i]);
+  }
+  free(lights);
+  free(lights2);
+
+  return 0;
+}