1 files changed, 75 insertions, 0 deletions
diff --git a/day12/day12.c b/day12/day12.c
new file mode 100644
index 0000000..2147c13
--- /dev/null
+++ b/day12/day12.c
@@ -0,0 +1,75 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define ungetchar(ch) ungetc(ch, stdin)
+
+int getnumber(char* input, int* i) {
+  int ch, num = 0, neg = 0;
+
+  if(input[(*i)++] == '-') {
+    ch = input[(*i)++];
+
+    if(ch < '0' || ch > '9')
+      return 0;
+    else
+      neg = 1;
+  }
+  (*i)--;
+
+  while((ch = input[(*i)++]) >= '0' && ch <= '9')
+    num = (num * 10) + (ch - 48);
+  (*i)--;
+
+  if(neg)
+    return -num;
+  else
+    return num;
+}
+
+int sumnumbers(char* input) {
+  int tot = 0, ch, i = 0;
+
+  while((ch = input[i++]) != '\0') {
+    if((ch >= '0' && ch <= '9') || ch == '-') {
+      i--;
+      tot += getnumber(input, &i);
+    }
+  }
+
+  return tot;
+}
+
+int sumnonred(char* input) {
+  return 0;
+}
+
+char* readtheinput() {
+  char *theinput, ch;
+  int i = 0, max = 1024;
+    
+  theinput = (char*) malloc(max * sizeof(char));
+
+  while((ch = getchar()) != EOF) {
+    theinput[i++] = ch;
+    if(i == max) {
+      max += 1024;
+      theinput = (char*) realloc((void*) theinput, max * sizeof(char));
+    }
+  }
+
+  theinput[i] = '\0';
+
+  return theinput;
+}
+
+int main() {
+  char* theinput;
+
+  theinput = readtheinput();
+
+  printf("Sum of all numbers: %d\n", sumnumbers(theinput));
+  printf("Sum of all non-red numbers: %d\n", sumnonred(theinput));
+
+  free(theinput);
+  return 0;
+}