Add solution for 2015 Day 25

src/2015/Day25.cpp

@@ -2,26 +2,33 @@
 
 namespace y2015::day25
 {
-  REGISTER_DAY(2015, Day25, std::vector<int>, int);
+  using Pair = std::pair<int, int>;
+  REGISTER_DAY(2015, Day25, Pair, int);
 
-  REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 1, 0);
-  REGISTER_TEST(2015, Day25, Input, 1, 0);
+  REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 1, 7981243);
+  REGISTER_TEST(2015, Day25, Input, 1, 8997277);
   REGISTER_TEST_EXAMPLE(2015, Day25, ExampleInput, 2, 0);
   REGISTER_TEST(2015, Day25, Input, 2, 0);
 
   READ_INPUT(input)
   {
-    std::vector<int> vec;
-    std::string str;
-    while (getline(input, str))
-    {
-    }
-    return vec;
+    int i1;
+    int i2;
+    input >> "To continue, please consult the code grid in the manual.  Enter the code at row " >> i2 >> ", column " >>
+      i1;
+
+    return std::pair{i1, i2};
+  }
+
+  int GetPower(const std::pair<int, int>& coordinate)
+  {
+    return (coordinate.first + coordinate.second - 1) * (coordinate.first + coordinate.second - 1 + 1) / 2 + 1 -
+           coordinate.second;
   }
 
   OUTPUT1(input)
   {
-    return 0;
+    return Helper::FastExponentiation(20151125, 252533, GetPower(input) - 1, 33554393);
   }
 
   OUTPUT2(input)