1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
package main
import (
"fmt"
"math"
"strconv"
)
func main() {
fmt.Println(expand([]int64{125, 17}, 25), 55312)
fmt.Println(expand([]int64{6, 11, 33023, 4134, 564, 0, 8922422, 688775}, 25), 220999)
fmt.Println(expand([]int64{6, 11, 33023, 4134, 564, 0, 8922422, 688775}, 75))
}
func evenLength(v int64) bool {
return int(math.Ceil(math.Log10(float64(v)+0.5)))%2 == 0
}
func splitEven(v int64) (a, b int64) {
s := strconv.FormatInt(v, 10)
sa, sb := s[:len(s)/2], s[len(s)/2:]
a, err := strconv.ParseInt(sa, 10, 64)
if err != nil {
panic(err)
}
b, err = strconv.ParseInt(sb, 10, 64)
if err != nil {
panic(err)
}
return
}
type Entry struct {
Value int64
Depth int
}
func expand(initial []int64, depth int) (result int) {
memo := make(map[Entry]int)
for _, n := range initial {
result += expandOne(memo, n, depth)
}
return
}
func expandOne(memo map[Entry]int, v int64, depth int) int {
if depth == 0 {
return 1
}
entry := Entry{v, depth}
n, ok := memo[entry]
if ok {
return n
}
if v == 0 {
n = expandOne(memo, 1, depth-1)
} else if evenLength(v) {
a, b := splitEven(v)
n = expandOne(memo, a, depth-1) + expandOne(memo, b, depth-1)
} else {
n = expandOne(memo, v*2024, depth-1)
}
memo[entry] = n
return n
}
|
