Merge branch 'master' into 'master'

using printf to avoid \n for pwd input message

newline after "Please enter Password: " looks strange

challenge/challenge.c

@@ -8,7 +8,7 @@ int main() {
     char *input_str = NULL;
     char *password = "23door42\n";
 
-    puts("Please enter Password: ");
+    printf("Please enter Password: ");
     ret = getline(&input_str, &nbytes, stdin);
 
     if (ret == -1) {