First attempt at a faster / more efficient implementation. This is orders of magnitude faster than the first, but still not nearly fast enough.

This commit is contained in:
Anna Rose Wiggins 2018-12-13 00:27:02 -05:00
parent fbd7c8fb00
commit 5d4757d4cb
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4 changed files with 102 additions and 0 deletions

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@ -0,0 +1,56 @@
package day12
func FastRunGeneration(plants []byte, rules map[string]byte, rootIndex int) ([]byte, int) {
newGen := make([]byte, len(plants), len(plants)+4)
for i := 0; i < len(plants); i++ {
newGen[i] = rules[getKey(plants, i)]
}
result1 := rules[getKey(plants, -2)]
result2 := rules[getKey(plants, -1)]
if result1 == '#' || result2 == '#' {
newGen = append([]byte{result1, result2}, newGen...)
rootIndex += 2
}
result1 = rules[getKey(plants, len(plants))]
result2 = rules[getKey(plants, len(plants)+1)]
if result1 == '#' || result2 == '#' {
newGen = append(newGen, result1, result2)
}
return newGen, rootIndex
}
func getKey(plants []byte, i int) string {
if i < 2 {
key := ""
for j := 0; j < 2-i; j++ {
key += "."
}
key += string(plants[0 : i+2])
return key
}
if i > len(plants)-2 {
key := string(plants[i-2 : len(plants)-1])
for j := 0; j < len(plants)-1-i; j++ {
key += "."
}
key += string(plants[0 : i+2])
return key
}
return string(plants[i-2 : i+2])
}
func FastSumPlants(plants []byte, rootIndex int) int {
sum := 0
for index, value := range plants {
if value == '#' {
sum += index - rootIndex
}
}
return sum
}