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copy image from cachedImages

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onyx-and-iris 2023-12-15 00:53:14 +00:00
parent 94ffd625c9
commit eab63b0b36
1 changed files with 11 additions and 9 deletions
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18
day-14/two.go
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@ -12,26 +12,28 @@ func cycleOnce(image img) {
}
// cycleMany cycles a single image for a given number of iterations
// it also caches the index of the iteration for each image
// it caches seen images as well as their location in the period
// finally it copies the cached image with idx matching the interval to image.raw
func cycleMany(image img, iterations int) {
cache := make(map[string]int)
cachedIndexes := make(map[string]int)
cachedImages := make(map[int][]string)
i, start := 0, 0
for ; i < iterations; i++ {
cycleOnce(image)
if idx, ok := cache[image.String()]; ok { // we found first repeated image
if idx, ok := cachedIndexes[image.String()]; ok { // we found first repeated image
start = idx
i++
break
}
cache[image.String()] = i + 1
cachedIndexes[image.String()] = i + 1
cachedImages[i+1] = make([]string, len(image.raw))
copy(cachedImages[i+1], image.raw)
}
period := i - start // length of a full period
remaining := (iterations - i - 1) % period // number of cycles left in current period
for j := 0; j < remaining; j++ {
cycleOnce(image) // rotate to the final image in the period
}
copy(image.raw, cachedImages[start+((iterations-i-1)%period)]) // copy cachedImage into image.raw
}
// two returns the load of all boulders after 1000000000 cycles