69 lines
1.2 KiB
Go
69 lines
1.2 KiB
Go
package main
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import (
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"fmt"
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"math"
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"strconv"
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)
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func main() {
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fmt.Println(expand([]int64{125, 17}, 25), 55312)
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fmt.Println(expand([]int64{6, 11, 33023, 4134, 564, 0, 8922422, 688775}, 25), 220999)
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fmt.Println(expand([]int64{6, 11, 33023, 4134, 564, 0, 8922422, 688775}, 75))
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}
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func evenLength(v int64) bool {
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return int(math.Ceil(math.Log10(float64(v)+0.5)))%2 == 0
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}
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func splitEven(v int64) (a, b int64) {
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s := strconv.FormatInt(v, 10)
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sa, sb := s[:len(s)/2], s[len(s)/2:]
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a, err := strconv.ParseInt(sa, 10, 64)
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if err != nil {
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panic(err)
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}
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b, err = strconv.ParseInt(sb, 10, 64)
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if err != nil {
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panic(err)
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}
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return
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}
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type Entry struct {
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Value int64
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Depth int
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}
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func expand(initial []int64, depth int) (result int) {
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memo := make(map[Entry]int)
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for _, n := range initial {
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result += expandOne(memo, n, depth)
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}
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return
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}
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func expandOne(memo map[Entry]int, v int64, depth int) int {
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if depth == 0 {
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return 1
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}
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entry := Entry{v, depth}
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n, ok := memo[entry]
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if ok {
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return n
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}
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if v == 0 {
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n = expandOne(memo, 1, depth-1)
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} else if evenLength(v) {
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a, b := splitEven(v)
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n = expandOne(memo, a, depth-1) + expandOne(memo, b, depth-1)
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} else {
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n = expandOne(memo, v*2024, depth-1)
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}
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memo[entry] = n
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return n
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}
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