Use nullable types for monkey return

Author: fwcd

day22/experiments/day22.cpp

@@ -25,7 +25,7 @@ int64_t prng(int64_t secret, int64_t n) {
   return secret;
 }
 
-int64_t monkey(int64_t secret, int64_t x1, int64_t x2, int64_t x3, int64_t x4) {
+std::optional<int64_t> monkey(int64_t secret, int64_t x1, int64_t x2, int64_t x3, int64_t x4) {
   std::optional<int64_t> d1, d2, d3, d4;
   for (int64_t i = 0; i < LIMIT; i++) {
     int64_t lastPrice = secret % 10;
@@ -39,15 +39,15 @@ int64_t monkey(int64_t secret, int64_t x1, int64_t x2, int64_t x3, int64_t x4) {
       return price;
     }
   }
-  return -1;
+  return std::nullopt;
 }
 
 int64_t score(std::vector<int64_t> input, int64_t x1, int64_t x2, int64_t x3, int64_t x4) {
   int64_t sum = 0;
   for (int64_t n : input) {
-    int64_t price = monkey(n, x1, x2, x3, x4);
-    if (price > 0) {
-      sum += price;
+    std::optional<int64_t> price = monkey(n, x1, x2, x3, x4);
+    if (price.has_value()) {
+      sum += *price;
     }
   }
   return sum;

day22/src/day22.dart

@@ -20,7 +20,7 @@ int prng(int secret, int n) {
   return secret;
 }
 
-int monkey(int secret, int x1, int x2, int x3, int x4) {
+int? monkey(int secret, int x1, int x2, int x3, int x4) {
   int? d1 = null, d2 = null, d3 = null, d4 = null;
   for (var i = 0; i < LIMIT; i++) {
     int lastPrice = secret % 10;
@@ -31,14 +31,14 @@ int monkey(int secret, int x1, int x2, int x3, int x4) {
       return price;
     }
   }
-  return -1;
+  return null;
 }
 
 int score(List<int> input, int x1, int x2, int x3, int x4) {
   int sum = 0;
   for (int n in input) {
-    int price = monkey(n, x1, x2, x3, x4);
-    if (price > 0) {
+    int? price = monkey(n, x1, x2, x3, x4);
+    if (price != null) {
       sum += price;
     }
   }