Day 20

day20/common/mixing.go

@@ -0,0 +1,105 @@
+package common
+
+import (
+	"bufio"
+	"strconv"
+)
+
+
+type Arrangement struct {
+  numbers []int
+}
+
+
+func (arrangement *Arrangement) Mix(number int) {
+  newSequence := make([]int, len(arrangement.numbers))
+  oldIndices := make([]int, 0, len(arrangement.numbers))
+  var newIndex int
+
+  for i := range arrangement.numbers {
+    oldIndices = append(oldIndices, i)
+    newSequence[i] = arrangement.numbers[i]
+  }
+
+  for i := 0; i < number; i++ {
+    currentIndices := make([]int, len(oldIndices))
+    for j := range oldIndices {
+      currentIndices[j] = oldIndices[j]
+    }
+
+    for j := 0; j < len(oldIndices); j++ {
+      offset := currentIndices[j]
+      currentNumber := arrangement.numbers[j]
+      newIndex = offset + currentNumber
+      newIndex = (newIndex % (len(newSequence) - 1) + len(newSequence) - 1) % (len(newSequence) - 1)
+
+      if offset == 0 {
+        newSequence = newSequence[1:]
+      } else if offset == len(newSequence) - 1 {
+        newSequence = newSequence[:len(newSequence) - 1]
+      } else {
+        newSequence = append(newSequence[:offset], newSequence[offset + 1:]...)
+      }
+
+      if newIndex == 0 {
+        newSequence = append([]int{currentNumber}, newSequence...)
+      } else if newIndex == len(newSequence) {
+        newSequence = append(newSequence, currentNumber)
+      } else {
+        newSequence = append(newSequence[:newIndex+1], newSequence[newIndex:]...)
+        newSequence[newIndex] = currentNumber
+      }
+
+      for i := range currentIndices {
+        if newIndex <= currentIndices[i] && currentIndices[i] < offset {
+          currentIndices[i]++
+        } else if offset < currentIndices[i] && currentIndices[i] <= newIndex {
+          currentIndices[i]--
+        }
+      }
+      currentIndices[j] = newIndex
+
+      offset %= len(newSequence)
+    }
+
+    for i := range currentIndices {
+      oldIndices[i] = currentIndices[i]
+    }
+  }
+
+  arrangement.numbers = newSequence
+}
+
+func (arrangement *Arrangement) ApplyDecryptionKey(key int) {
+  for i := range arrangement.numbers {
+    arrangement.numbers[i] *= key
+  }
+}
+
+func (arrangement *Arrangement) GetCoordinates() (int, int, int) {
+  var locationOf0 int
+  for i := range(arrangement.numbers) {
+    if arrangement.numbers[i] == 0 {
+      locationOf0 = i
+    }
+  }
+
+  x := arrangement.numbers[(locationOf0 + 1000) % len(arrangement.numbers)]
+  y := arrangement.numbers[(locationOf0 + 2000) % len(arrangement.numbers)]
+  z := arrangement.numbers[(locationOf0 + 3000) % len(arrangement.numbers)]
+
+  return x, y, z
+}
+
+
+func Parse(scanner bufio.Scanner) Arrangement {
+  arrangement := Arrangement{}
+
+  for scanner.Scan() {
+    line := scanner.Text()
+    number, _ := strconv.Atoi(line)
+    arrangement.numbers = append(arrangement.numbers, number)
+  }
+
+  return arrangement
+}