1 files changed, 71 insertions, 0 deletions
diff --git a/day11/day11.c b/day11/day11.c
new file mode 100644
index 0000000..3a12820
--- /dev/null
+++ b/day11/day11.c
@@ -0,0 +1,71 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+char* incr(char password[8]) {
+  int i, rollover = 1;
+
+  for(i = 7; (i >= 0) && rollover; i--) {
+    if(password[i] == 'z') {
+      password[i] = 'a';
+    } else {
+      password[i] += 1;
+      rollover = 0;
+    }
+  }
+
+  return password;
+}
+
+char check(char* password) {
+  char i, flags = 2, firstpair = 0;
+
+  for(i = 0; i < 5; i++)
+    if(password[i+1] == password[i] + 1 && password[i+2] == password[i] + 2)
+      flags |= 1;
+
+  for(i = 0; i < 8; i++)
+    if(password[i] == 'i' || password[i] == 'o' || password[i] == 'l')
+      flags &= (~2);
+
+  for(i = 0; i < 7; i++) {
+    if(password[i] == password[i+1]) {
+      if(firstpair) {
+        if(password[i] != firstpair)
+          flags |= 4;
+      }
+      else
+        firstpair = password[i];
+      i++;
+    }
+  }
+
+  return (flags == 7);
+}
+
+char* next(char* password) {
+  char good = 0;
+
+  while(!good) {
+    password = incr(password);
+    good = check(password);
+  }
+
+  return password;
+}
+
+int main() {
+  char *password;
+  password = malloc(10*sizeof(char));
+  scanf("%s", password);
+
+  password = next(password);
+  printf("First new password: %s\n", password);
+
+  password = next(password);
+  printf("Second new password: %s\n", password);
+
+  free(password);
+
+  return 0;
+}