Add d1p1 faf

src/day1/p1/faf.cpp

@@ -89,14 +89,13 @@ int main() {
         auto [next, ec] = std::from_chars(ptr, end, number);
         ptr = next;
 
-        while (ptr < end && (*ptr == '\n' || *ptr == '\r')) {
-            ++ptr;
-        }
+        if (ptr < end && *ptr == '\r') ++ptr;
+        if (ptr < end && *ptr == '\n') ++ptr;
 
         if (is_right) {
             state = (state + number) % 100;
         } else {
-            state = (state - number % 100 + 100) % 100;
+            state = (state + 100 - number % 100) % 100;
         }
 
         password += (state == 0);