Big update: Adding all advent of codes to same repo

AdventOfCode2020/day25/day25.go

@@ -0,0 +1,40 @@
+package main
+
+import "fmt"
+
+func main() {
+  var dividerr int64 = 20201227
+  // var cardPKey int64 = 5764801
+  // var doorPKey int64 = 17807724
+
+  var cardPKey int64 = 16915772
+  var doorPKey int64 = 18447943
+
+  var cardValue int64 = 1
+  var cardLoopSize int64 = 0
+
+  for cardValue != cardPKey {
+    cardValue *= 7 // Subject number
+    cardValue = cardValue % dividerr
+    cardLoopSize++
+  }
+
+  var doorValue int64 = 1
+  var doorLoopSize int64 = 0
+
+  for doorValue != doorPKey {
+    doorValue *= 7 // Subject number
+    doorValue = doorValue % dividerr
+    doorLoopSize++
+  }
+
+  var part1 int64 = 1
+  var i int64 = 0
+  
+  for i = 0; i < cardLoopSize; i++ {
+    part1 *= doorPKey
+    part1 = part1 % dividerr
+  }
+
+  fmt.Printf("Part 1: %d %d %d\n", cardLoopSize, doorLoopSize, part1)
+}