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day5_1.go
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/
day5_1.go
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package main
import (
"bytes"
"fmt"
"io/ioutil"
"log"
"os"
)
func main() {
buf, err := ioutil.ReadAll(os.Stdin)
if err != nil {
log.Fatal(err)
}
in := string(bytes.TrimSpace(buf))
out := react(in)
fmt.Println(len(in), len(out))
}
func react(p string) string {
var in, out []byte
in = []byte(p)
for {
out = out[:0]
for i := 1; i <= len(in); i++ {
if i < len(in) && reduce(in[i-1], in[i]) {
i++
continue
}
out = append(out, in[i-1])
}
if bytes.Compare(in, out) == 0 {
return string(in)
}
in, out = out, in
}
}
func reduce(a, b byte) bool {
if (a >= 'a') == (b >= 'a') {
return false
}
return element(a) == element(b)
}
func element(b byte) byte {
if b >= 'a' {
return b
}
return b - 'A' + 'a'
}